There is a wide scope of "cooperation with US", from extradition treaties (so the US could demand the operator be legally extradited & jailed as opposed to kidnapped) to mutual legal assistance treaties (police collaboration), to "cybersecurity agreements". And the US military/economic strength (such as their control of SWIFT or the widespread military and "intelligence" apparatus) means very few countries won't cooperate. The US does not follow international law unless it wants to.
US most often collaborates with EU & Anglosphere countries (UK "commonwealth" countries).
Comparison of NSA spying collaboration (known)
https://restoreprivacy.com/5-eyes-9-eyes-14-eyes/
NSA are also interested in undersea cable wiretapping:
https://www.vice.com/en/article/wnnmv9/undersea-cable-surveillance-is-easy-its-just-a-matter-of-money
https://www.theatlantic.com/international/archive/2013/07/the-creepy-long-standing-practice-of-undersea-cable-tapping/277855/
Extradition:
https://qz.com/97428/map-how-to-stay-out-of-reach-of-us-extradition-treaties/
Note that they could probably use a third country that has treaties with both the US and the country where the operator is located.
The NSA also works to gather information before it is encrypted, or to weaken random number generators and encryption schemes.
https://www.schneier.com/blog/archives/2013/09/good_summary_of.html
https://www.zdnet.com/article/has-the-nsa-broken-ssl-tls-aes/
https://www.schneier.com/blog/archives/2012/03/can_the_nsa_bre.html
Intel ME is a good example, also keyloggers, hardware surveillance devices.
https://news.softpedia.com/news/intel-x86-cpus-come-with-a-secret-backdoor-that-nobody-can-touch-or-disable-505347.shtml
Intel ME can be set to disable (ironically thanks to NSA), but since it's proprietary, you can't be certain. AMD and other chip makers likely have similar subsystems.
https://privacysos.org/blog/did-this-tor-developer-become-the-first-known-victim-of-the-nsas-laptop-interception-program/
Oh and NSA is allowed to share with FBI.
https://www.rt.com/usa/373644-new-rules-access-nsa-data/
There is a wide scope of "cooperation with US", from extradition treaties (so the US could demand the operator be legally extradited & jailed as opposed to kidnapped) to mutual legal assistance treaties (police collaboration), to "cybersecurity agreements". And the US military/economic strength (such as their control of SWIFT or the widespread military and "intelligence" apparatus) means very few countries won't cooperate. The US does not follow international law unless it wants to. US most often collaborates with EU & Anglosphere countries (UK "commonwealth" countries).
Comparison of NSA spying collaboration (known) https://restoreprivacy.com/5-eyes-9-eyes-14-eyes/ NSA are also interested in undersea cable wiretapping: https://www.vice.com/en/article/wnnmv9/undersea-cable-surveillance-is-easy-its-just-a-matter-of-money https://www.theatlantic.com/international/archive/2013/07/the-creepy-long-standing-practice-of-undersea-cable-tapping/277855/
MLAT data: https://web.archive.org/web/20180325141949/https://www.mlat.info/
Extradition: https://qz.com/97428/map-how-to-stay-out-of-reach-of-us-extradition-treaties/ Note that they could probably use a third country that has treaties with both the US and the country where the operator is located.
The NSA also works to gather information before it is encrypted, or to weaken random number generators and encryption schemes. https://www.schneier.com/blog/archives/2013/09/good_summary_of.html https://www.zdnet.com/article/has-the-nsa-broken-ssl-tls-aes/ https://www.schneier.com/blog/archives/2012/03/can_the_nsa_bre.html Intel ME is a good example, also keyloggers, hardware surveillance devices. https://news.softpedia.com/news/intel-x86-cpus-come-with-a-secret-backdoor-that-nobody-can-touch-or-disable-505347.shtml Intel ME can be set to disable (ironically thanks to NSA), but since it's proprietary, you can't be certain. AMD and other chip makers likely have similar subsystems. https://privacysos.org/blog/did-this-tor-developer-become-the-first-known-victim-of-the-nsas-laptop-interception-program/
Oh and NSA is allowed to share with FBI. https://www.rt.com/usa/373644-new-rules-access-nsa-data/