Iranian assassination, and he's backing a huge proxy war in Yemen that has been devastating. I'm sure the "Made in the USA" bomb fragments on the ground that blew up Yemeni children will be attributed only to the Saudis and not the US.
Trump is culpable for much, but technically the conflict in Yemen started before he was president. The claim above still seems accurate, though I think we can safely say such a claim is damning with faint praise.
I'm referring to the Trump-ordered assassination of Qasem Soleimani. He was Iran's equivalent of the Secretary of Defense, and also a folk-hero to Iranians. Soleimani was assassinated by US drone strike in January 2020.
Iran responded with a carefully-targeted retaliation - a small missile strike against an unused/unmaintained US military installation in Iraq. There were no casualties.
Iran chose a target with low strategic value and no personnel present. Just enough of a strike that they could sell it as retaliation, but not enough of a strike to escalate into a full war.
I won't pretend to know if the assassination was warranted or necessary. But it's easily something that Iran could have used to justify a war.
Unfortunately, the stable genius in the WH does.