While there may be a legal dimension to this issue there is a more compelling moral one.
Who brings the Americans to justice? Who puts them on trial? Who holds them accountable for crimes against humanity? For killing people with impunity and without trial? For torturing people for over a decade? For destroying entire nations? For invading countries based on a lie?

American soldiers did everything from urinating on the graves of fallen Taliban to, using drones to kill ordinary citizens extra judicially, to pulling the bullets out of the bodies of Afghan women to hide the fact from the authorities, to mowing down journalists with helicopter gunships.

The USA cannot have it both ways - they cannot bully their allies into obeying the law without following those same laws. This is why the US has lost its leadership in the world. The institutions it helped create  have been abused by the very nation that benefits the most from them. The USA is the architect of its own demise.