That's a long story, going back before the foundation of the Russian Empire, let alone the Soviet Union or Russian Federation. The most recent history is that in 2014 Russia invaded Ukraine with the support of (and to support) separatists in two eastern areas of Ukraine. They captured Crimea (a strategic peninsula with an important naval base) but pulled out of the eastern areas and since then the Ukrainian army has made some gains against the separatists, although they are not at all defeated (it's devolved into static trench warfare in some areas).
Russia moved 100,000 troops to their western border with Ukraine, and are adding more all the time. They say it's no big deal but 100,000 troops are really expensive to keep out of their home bases for any length of time, so it's unlikely that they would just do this on a whim.
Ukraine's government wants to join NATO, but the process has been moving slowly due to the instability in the disputed areas and the general shift in the way the Ukrainian army would have to operate.
Nobody knows, probably not even Putin (he's waiting to see if he can get more concessions out of the west or Ukraine). My best guess is that the Russians will try to drive Ukrianian forces completely out of the separatist areas and try to stabilize them, and also attempt to capture a land corridor that connects Crimea with the Russian mainland for ease of supplying power and water. Without significant foreign help (that would by this point probably come too late), the Ukrainian army will probably not be able to resist them.
That's a long story, going back before the foundation of the Russian Empire, let alone the Soviet Union or Russian Federation. The most recent history is that in 2014 Russia invaded Ukraine with the support of (and to support) separatists in two eastern areas of Ukraine. They captured Crimea (a strategic peninsula with an important naval base) but pulled out of the eastern areas and since then the Ukrainian army has made some gains against the separatists, although they are not at all defeated (it's devolved into static trench warfare in some areas).
Russia moved 100,000 troops to their western border with Ukraine, and are adding more all the time. They say it's no big deal but 100,000 troops are really expensive to keep out of their home bases for any length of time, so it's unlikely that they would just do this on a whim.
Ukraine's government wants to join NATO, but the process has been moving slowly due to the instability in the disputed areas and the general shift in the way the Ukrainian army would have to operate.
Nobody knows, probably not even Putin (he's waiting to see if he can get more concessions out of the west or Ukraine). My best guess is that the Russians will try to drive Ukrianian forces completely out of the separatist areas and try to stabilize them, and also attempt to capture a land corridor that connects Crimea with the Russian mainland for ease of supplying power and water. Without significant foreign help (that would by this point probably come too late), the Ukrainian army will probably not be able to resist them.