Forget About Everything Else...

[SilverFang01]

It being possibly illegal outside specific circumstances may not be a deterrent anymore since Trump has shown he'll absolutely pardon American military personnel that commit war crimes.

Except that warcrimes are a matter of international law, and a pardon by the USA federal government may not be enough of a shield. Because while it's generally preferred for such cases to be tried by the nation those military personnel work for, if such trials do not happen it's entirely within the bounds of the treaties for any other belligerent or the UN to demand and arrange such trials.

After all, both Nuremberg and the various warcrime tribunals performed in The Hague set that precedent. Or did you think Yugoslavia or its relevant successor states were all that happy that key, high ranking military personnel were abducted from their borders to stand trial?

America being the proverbial 800 pound gorilla doesn't actually help here, not when it's not impossible the EU as a whole tell the USA to pound sand when it comes to putting people who are extremely unpopular in the USA on trial, and the USA decides it's not worth the effort to enforce them conducting the trials themselves, or force the UN and the EU to stop. It does require a certain degree of egregious violence on the part of the USA when engaging Iran though, if things come to blows.

In the good timeline, that would be the case, unfortunately the Bush administration passed the

The American Service-Members' Protection Act (ASPA, Title 2 of Pub.L. 107–206, H.R. 4775, 116 Stat. 820, enacted August 2, 2002) is a United States federal law that aims "to protect United States military personnel and other elected and appointed officials of the United States government against criminal prosecution by an international criminal court to which the United States is not party." Introduced by U.S. Senator Jesse Helms (R-NC) and U.S. Representative Tom DeLay (R-TX)[1] it was an amendment to the 2002 Supplemental Appropriations Act for Further Recovery From and Response to Terrorist Attacks on the United States (H.R. 4775).[2] The bill was signed into law by U.S. President George W. Bush on August 2, 2002.

ASPA authorizes the U.S. president to use "all means necessary and appropriate to bring about the release of any U.S. or allied personnel being detained or imprisoned by, on behalf of, or at the request of the International Criminal Court". This authorization has led the act to be nicknamed the "Hague Invasion Act".[3][4]

And as far as I know, this piece of legislative stupidity has not been repealed. They may think of it as their “get out of jail free” card.