Mattis is one of the people in the Trump administration proposing increased U.S. support for the war on Yemen:

Defense Secretary Jim Mattis has asked the White House to lift Obama-era restrictions on U.S. military support for Persian Gulf states engaged in a protracted civil war against Iranian-backed Houthi rebels in Yemen, according to senior Trump administration officials.

In a memo this month to national security adviser H.R. ­McMaster, Mattis said that “limited support” for Yemen operations being conducted by Saudi Arabia and the United Arab Emirates — including a planned Emirati offensive to retake a key Red Sea port — would help combat a “common threat.”

Mattis is wrong about this, and his request should be rejected. The restrictions that the Obama administration put in place shortly before leaving office were a belated, half-hearted gesture ostensibly aimed at protesting indiscriminate coalition attacks on civilian targets. It was far too little, much too late, but it was better than nothing. Lifting those restrictions would tell the coalition that the new administration has no problem with the way they have been conducting their campaign, and it will encourage them to be even more reckless and irresponsible than they have been.

Giving the coalition even more support at this point would further implicate the U.S. in their war crimes, and backing an offensive on Hodeidah would make a horrifying humanitarian disaster in the country even worse. Millions are on the brink of famine in large part because of the Saudi-led intervention and blockade. More attacks on the port will push many of them over the brink. Increasing U.S. support would just deepen our complicity in wrecking and starving Yemen, and there can be no justification for doing that.

On top of that, the justification that Mattis gives is a bad one. It is important to emphasize that the coalition’s enemies in Yemen don’t pose a threat to the U.S., and the little support they receive from Iran has never warranted our involvement in this war. Mattis’ “common threat” rhetoric is based in a dangerous misunderstanding of the conflict. If Trump agrees to Mattis’ request, it will lead the administration to escalate U.S. involvement in a war in which we should have no part. The people of Yemen are already paying a terrible, steep price as a result of a war that our government has enabled for two years, and doing more to back the Saudis and their allies will achieve nothing except to inflict even more harm on the civilian population.