Under the Constitution of the United States, only Congress has the authority to declare war. That has not occurred since WWII, so ALL military occupations outside the US are illegal. There is a "War Powers Act" of 1973 that granted the Executive branch (President) 60 days to wage a war before asking Congress for permission. It is that re-extension of 60 days that the President has abused. All military actions are illegal, so all military kills are legal murders.
The President of the United States (and all prior Presidents) can be charged with murder. There is no defense. Why hasn't this occurred? Because the legal community refuses to do so and the general population is mostly unaware.
Also. There is no such thing as a "military police action" visa, so all military occupations can be deported via immigration law.