[Theoria]

'What should be the limits of actions the US can take against its own citizens who aid organizations that want to kill Americans?'

Because he is a citizen, and citizens have rights in our form of government. .Gov can't simply say, he is a bad dude, and have determined he is a bad dude without any open court or procedure. Being overseas does not limit .gov, they are still bound by the Constitution.

[driftdiver]

Sounds good in theory. They’ve been throwing the Constitution away on a daily basis.