left wing parties are correct in their critiques about capitalism and corporations but seem to have a blind spot against their own imperialism on the Global South and even keen on perpetuating anti-China propaganda.

I don't know who in the US this describes besides half of DSA and anarchists

Most Soc-Dems are people who were born into the top 10% of wealth in their society rather than the top 1%, and it’s their bitterness about that which drives them. This squabbling among the upper classes has been the great conflict of Western politics since before the French Revolution (the original lines being the aristocracy vs the emerging power of the bourgeoisie). These people don’t even know what imperialism is, at least not as we understand it - and the welfare state is only a sort of part charity part bribe to placate the working class, rather than the product of a belief in equality. To us it looks it like European soc-Dems are resigned to being US pawns, but a lot of them are genuinely in love with the idea of America, as all liberals are.

As far as US liberals go I think it's driven more by ideology than material interests. Unless you actually work in the military industrial complex, you're unlikely to get any benefit from supporting the war in Ukraine, for instance.

In the US, there are basically two acceptable positions with regard to foreign policy:

1. The US is magnanimous and aims to be a force for good in the world, and apart from a couple hiccups and honest mistakes (mostly caused by the other side), it generally succeeds at that. We must fund the military as much as possible and oppose anyone who could challenge our hegemony so that we can keep bringing democracy and freedom to the backwards, uncivilized people of the world.

2. The US is magnanimous and aims to be a force for good in the world, and this is a bad thing on the basis that the lives of non-Americans are worthless. Trying to do good things abroad is even worse than trying to do good things at home, which is bad because it's communism. We should fund the military as much as possible so that we can take whatever we want from anyone who can't defend themselves and other people can't take stuff from us.

These positions can track directly with the two prevailing historical perspectives regarding settler-colonialism. The "progressive" perspective was that the natives were only backwards, evil savages because their backwards, evil, savage culture taught them to be. You could remove a native child from their culture and raise them as a Westerner, and they could be just as civilized as any other Westerner, and their aim was to do this and seek to eradicate cultures in order to bring people into the fold of civilization. The "less progressive" perspective was that the reason they were "uncivilized" was not because of their upbringing but an inherent quality of their race. The perspective that the culture and way of life of native people is worth preserving and that Western culture is not inherently superior was not present in the discourse at all, as that would imply full-on opposition to the entire settler-colonial project.

Liberals will never restrain themselves in supporting imperialism because they believe that any opposition to their project must be grounded in racism or nationalism. They haven't fundamentally changed or questioned their assumptions from the old times when they were eradicating native cultures, and the idea that someone could be opposed to their whole entire project on a non-self-centered basis just doesn't compute.

Conservatives sometimes, occasionally, rarely restrain themselves because they don't believe in that project and just want to take people's stuff, and when you just want to take people's stuff, then you have to consider whether their stuff is worth taking and how well defended the stuff is. There's the most basic possible level of cost-benefit analysis, which still somehow beats liberal takes sometimes just because liberals don't even bother with that at all.

A lot of good answers here and I agree with most of them.

One factor I think not being discussed is how this difference changes between electoralist and non-electoralist groups.

To be an electoralist you simply can not cross certain lines without fundamentally alienating yourself from the people who own all the media. Electoral gains within the imperial core come from making a deal with the devil which happens to be whoever owns the majority of the media in the country.

Gaining power comes before principles for electoralist socdems and liberals.

I do not see many non-electoral groups who are pro-imperialism.

Why do Western progressive left (both US and especially the European parties) support imperialism?

Some of them don't actually conceive of what their countries are doing as "imperialism" (at least, in the Leninist use of the term) and think that's a thing that only Bad Evil Authoritarian countries do. This is the most useless type of progressive, you find them everywhere on ostensibly left-leaning areas on Reddit, Twitter, TikTok, Tumblr, etc. Their purpose in the imperial apparatus is to do the "I'm as far left as they come, literally an anarchist/communist, screw the pigs, but look, we gotta support NATO against Russia..." routine.

Some of them are perfectly aware that what Western countries are doing is imperialism, but are afraid to make opposition to that imperialism one of their main goals because they fear either a) alienating the people around them who benefit from the imperialist arrangements, or b) state reprisal, because of course those imperialist arrangements are what keeps the West functioning as a coherent entity and so any opposition to that must be crushed; trying to make changes to other issues like the environment and progressive social reform are variably allowed or disallowed depending on the circumstances and the flavour of capitalist party in charge but the empire and military must never be touched or remarked on negatively.

the left wing parties are correct in their critiques about capitalism and corporations but seem to have a blind spot against their own imperialism on the Global South and even keen on perpetuating anti-China propaganda.

What left wing parties are these? There are certainly no major ones in the US. The two largest formations that actually criticize capitalism are PSL and a few caucuses in DSA. PSL is anti-imperialist and defends against imperialist attacks on China. Red Star caucus in DSA does as well. There are DSA caucuses that criticize capitalism and are still imperialism. These are either Trot or are Bernie liberals that retain substantial reactionary sentiment and are quite ignorant.

In the US, liberalism and imperialist apologetics are the baseline. Most people are politically illiterate in a deep sense and have nobody around to explain why they are exploited or how it is connected to exported violence. Most don't even know about the exported violence. When they are informed they often recede and become defensive, having been raised in a culture where not knowing something is an unforgivable weakness and politics is about being in camp A or B where the camps differentiate themselves by how explicit their racism is.

Really, your question is asking why there are no popular and proper socialist parties in the imperial core.

First, it is very difficult to have non-socialist anti-imperialist parties in the imperial core because they are in the oppressor country and have no framework by which to accidentally become anti-imperialist - and their entire state apparatus is set up around imperial extraction. You can see some legacy anti-imperialism in e.g. Ireland due to their recent history of resisting colonization, though their best anti-imperialists are still socialist. The closest that non-socialist parties come to anti-imperialist stances is through anti-warism. They don't know what imperialism is, how it ties to the economic system, etc. They draw on a simple moralism of seeing war and being against it. They might say "no wars for oil" and be accidentally correct due to the petrodollar and a need to control trade and use energy as a weapon. But they are easily coopted because they don't understand power or build out orgs realistically. The idea of building and using leverage never enters the equation. They are fundamentally idealists and there are large propaganda apparatuses that reaffirm their ineffectual idealism.

So then the question vis why aren't there major socialist parties in the West? Why are they all liberal parties that want social programs, labor imperialists, and reactionary legacy parties? That would take a long time to properly answer. It is many things. Propaganda. Gladio. Red scare. The education system. Bad organizing. Being "bought off" with treats and/or free equity.

To me, the question should be what success looks like, what you hope to achieve, and how to realistically work towards that goal given a historical education in failures. Look to what is currently deficient and ask how to change it and see who stands in your path. Becoming familiar with real OTG failures, if stagnating organizations, of anti-imperialist work that accomplishes nothing, these are the important questions. And they should be inverted: how do you grow your org? How do you set real and material goals and achieve them? Who do you work with? How do you educate? How will you protect yourself?

I think a lot of analysis here are missing the fact that the Western progressive left is also stupid and incompetent. Where does this stupidity and incompetence lie? It ties back to how the material interests of the imperial core lie with upholding imperialism. The smart and competent people know where their bread is buttered and are open supporters of imperialism. If they are not materially supporting imperialism like working for Lockheed Martin or having a career in the military bombing brown kids in an air-conditioned room in Phoenix, they are using their intelligence and competence to climb the corporate ladder at the expense of others. It's the stupid and incompetent who join progressive parties thinking they are helping somehow when they are still unconsciously guided to uphold imperialism.

This explains why the Greens in Germany are so anti-nuclear to the point of being materially detrimental to themselves. It's stupidity and incompetence all around. The smart Germans are just cynical and shameless Atlanticists who know the ticket to a good life is to sell off their country to the Burgerlanders while the stupid Germans push hard for industrial policies that ensnare them to the whims of the Burgerlanders anyways. It's a difference between someone getting a slice of that $1.6 billion to shit on China and some progressive going "aktually, we don't support the CCP because they're authoritarian" without even getting a single paycheck from the CIA.

The bad news is that when the shit hits the fan and the material conditions are actually ripe for revolution, the stupid and incompetent people currently in charge of orgs will lead people off a cliff on account of their stupidity and incompetence. The orgs that can actually bring change need to either have their own Zunyi Conference where the stupid and incompetent are purged from power or be build at a time when the smart and competent know that the way forward is through anti-imperialism, not through collaboration with an imperialist regime.

its more that they just want a more equal share of the spoils from the global south instead of any actual change of the sistem

Instead it is the right wing nationalist parties that seem to want a closer cooperation with socialist China.

Cooperation with china is mostly pushed because they dont see china as a geopolitical enemy at the moment or they see another great power as a bigger threat (like how in the 15th-20h century european powers believe in the balance of power and would join temporary alliances between old rivals to weaken another who was getting too strong)

As for the use of western socdem parties there is none, Lenin talks about the betray of the second international of the Proletariat to back their nations during ww1, becoming active agents of imperialism and justifying this with saying it was a necesary sacrifice or they needed more reforms which all lead to nothing with the rise of fascism pre-ww2

I think there's one factor, particularly relevant in America, where offshoring of manufacturing decimated huge amounts of working class families, but the remaining manufacturing/industrial workers want to claw at whatever remains. Nowadays the primary goal of any industrial labor union in the core is maintaining job security above anything else, that's why you see unions calling against climate deals in the grounds that coal, oil, and gas are creating jobs for them. Same principle applies doubly or triply in the domain of arms manufacturers. There's a contradiction though, because under imperialism it doesn't make sense to keep an industrial base inside the core where wages are high, so if anything those unions should oppose imperialism, but the Leninist analysis has died out and very few people connect the export of financial capital to imperialist war, offshoring, and deindustrialization. Maybe you are right because those who do make the connection still value the privilege of belonging to the labor aristocracy above the gain from no longer competing with superexploited periphery workers.

In order to truly understand this contradiction, the most explosive contradiction capitalism has engendered, the centers/peripheries polarization must be placed at the heart of the analysis and not at its margin.

But after a whole series of concessions, the forces of the Left and of socialism in the West have finally given up on giving the imperialist dimension of capitalist expansion the central place that it must occupy both in critical analysis and in the development of progressive strategies. In so doing, they have been won over to bourgeois ideology in its most essential aspects: Eurocentrism and economism.

The very term imperialism has been placed under prohibition, having been judged to be unscientific. Considerable contortions are required to replace it with a more "objective" term like "international capital" or "transnational capital." As if the world were fashioned purely by economic laws, expressions of the technical demands of the reproduction of capital. As if the state and politics, diplomacy and armies had disappeared from the scene! Imperialism is precisely an amalgamation of the requirements and laws for the reproduction of capital; the social, national, and international alliances that underlie them; and the political strategies employed by these alliances.

It is therefore indispensable to center the analysis of the contemporary world on unequal development and imperialism. Then, and only then, does it become possible to devise a strategy for a transition beyond capitalism. The obstacle is disengaging oneself from the world system as it is in reality. This obstacle is even greater for the societies of the developed center than it is for those of the periphery. And therein lies the definitive implication of imperialism. The developed central societies, because both their social composition and the advantages they enjoy from access to the natural resources of the globe are based on imperialist surpluses, have difficulty seeing the need for an overall reorganization of the world. A popular, anti-imperialist alliance capable of reversing majority opinion is as a result more difficult to construct in the developed areas of the world. In the societies of the periphery, on the other hand, disengagement from the capitalist world system is the condition for a development of the forces of production sufficient to meet the needs and demands of the majority. This fundamental difference explains why all the breaches in the capitalist system have been made from the periphery of the system. The societies of the periphery, which are entering the period of "post-capitalism" through strategies that I prefer to qualify as popular and national rather than socialist, are constrained to tackle all of the difficulties that delinking implies.

[...]The discouragement that has overtaken the forces of socialism in the West, who find in the situation of the "socialist" countries an alibi for their own weaknesses, has its source elsewhere, in the depths of the Western societies themselves. As long as it does not have a lucid understanding of the ravages of Eurocentrism, Western socialism will remain at a standstill.

[...] Eurocentrism is a powerful factor in the opposite sense. Prejudice against the Third World, very much in favor today, contributes to the general shift to the right. Certain elements of the socialist movement in the West reject this shift, of course. But they do so most often in order to take refuge in another, no less Eurocentric, discourse, the discourse of traditional trade unionism, according to which only the mature (read European) working classes can be the bearers of the socialist future. This is an impotent discourse, in contradiction with the most obvious teachings of history.

• Samir Amin, Eurocentrism, For a Truly Universal Culture.

Liberal chauvinism. Conservative imperialists are almost always driving by a sense of national/ethnic chauvinism. Their right to dictate the affairs of the world comes from they believe to be their innate superiority as white westerners.

Liberals, on the other hand, beleive their "superior education" is what gives them the right to dictate the affairs of the world. If you ask the average Western liberal about how any problem will be fixed, you will inevitably.end up hearing an answer along the lines of "If the people who disagree with me simply had a better education, then these problems wouldn't exist." They went to the right schools, room the right classes, and got the right jobs. They simply know better than everyone else due to their superior education. If all the countries in the Global South simply let their University of Chicago-educated IMF economists come in and tell them what to do, then everything would straighten itself out. Because they are such more educated, they are thus able to also reason what is just, and thus, are always correct about when they need to use forced in order to force their education upon the rest of the world.

Is it because they understand that they would lose the privilege of being a Western high income economy if their imperialist machines can no longer continue to extract disproportionately unequal values from the Global South? If this is the case, what use is the European left progressivism/social democracy/socialism if its solution for a welfare state is deeply predicated on its ability to exploit the Global South?

Yes, you've got most of it. The other aspect is that decades of white supremacy, sinophobia, and chauvinism allows for rightwing fear mongering about the Chinese, the CPC, and communism. This creates the perfect cognitive environment for the most caustic propaganda against socialism and communism.

That's why Scandinavian "socialism" is acceptable to them, because it's white and hasn't suffered nearly as much from the aforementioned propaganda and ideologies that plague the western mind.

But make no mistake, the end result is the destruction of the welfare state and hyper individualism. Whether the destruction of the welfare state comes from inside (austerity and the like) or the outside (global southern countries successfully repelling western imperialism), the result is the same.

Tldr: western left is burdened by too much to actually be against imperialism in any meaningful way

It can be explain with the world-system theory of Wallerstein, the economic of the working class in the core countries are pegged onto the global north imperialist machine.

As the global north economy goes up the welfare of the working class goes up (as before globalization). However, if it goes down(80s and beyond), the working class still need to rely on the imperial machine to scrap the barrel

Why do Western progressive left (both US and especially the European parties) support imperialism?

Broadly, because it supports the Empire they live in. They wish to gain more of the spoils of the present society they live in, and genuinely lack analysis of Imperialism.

I need someone to explain this to me. It makes no sense. Is it because they understand that they would lose the privilege of being a Western high income economy if their imperialist machines can no longer continue to extract disproportionately unequal values from the Global South? If this is the case, what use is the European left progressivism/social democracy/socialism if its solution for a welfare state is deeply predicated on its ability to exploit the Global South?

You're placing too much faith in "leftists." Social Democracy in the Global North is acceptable because it has some of the highest metrics (as reported and determined by bourgeois media) on the planet, with no analysis of where those metrics come from, because confronting that is far harder to internalize and accept.

You're asking the Labor Aristocracy to work against their class interests with respect to the primary contradiction at the world stage, the internationalist element in the Global North is severely weakened by the fruits of Imperialism.

I ask myself this too as someone who is from the global south but I think your last paragraph might be it. My guess is that most of them are all talk and just wanna larp on issues that are more left-wing/progressive but at the end of the day they are still capitalists and value their own profit over actual liberation of the working class, be it their own, but especially of colonized countries. They take advantage of social issues like typically left-wing issues who also tend to be more popular with groups like youth and minorities and use it to draw in people who care about that but don't actually do anything that would radically bring about communism or liberation of the global south. The sad truth is that most of the western/european left, specifically the parties and politicians, put up a front for their own sake but are still capitalists and will much rather side with nazis and the like over any resistance fighter of any colonized nation to maintain the status quo enough as to not threaten their money, they are enemies and not allies when this is the case which sadly is the most common when we look at their foreign policies, they want to pacify their own working class so they can remain in power and enjoy the benefits they get of pillaging the global south. The few that are genuine dont really have any actual power inside the political structure as much as they might have with the people themselves. Hope I made myself sound reasonable here since its 2 am and english is hard but to me those people are simply not genuine and co-opting stuff for their own gain.