A recently House-passed bill, which seems likely to pass in the Senate, could mark President Trump's first veto in office.
Yemen has been mired in a civil war since March 2015, between the internationally-recognized government and an Islamic armed rebel group called the Houthis, along with their allies including ISIS and Al Qaeda in the Arabian Peninsula (AQAP). More than 60,000 people have died in the conflict to date.
Saudi Arabia, which borders Yemen to the north, has led a coalition of nations aiming to restore and reinforce the preexisting Yemeni government in power -- through airstrikes, bombing campaigns, and other military actions. The U.S. had been helping support that effort, across both the Obama and Trump administrations.
But since Saudi Arabia's Crown Prince Mohammed bin Salman was believed to have personally ordered or approved the murder of journalist Jamal Khashoggi in October, U.S. public sentiment has widely turned against the Saudi regime.
What the legislation does
House Joint Resolution 37 would prevent the U.S. from fighting in or assisting in Yemen's civil war, starting 30 days after the legislation passes.
The legislation, which does not appear to have an official name, was introduced on January 30 by Rep. Ro Khanna (D-CA17).
What supporters say
Supporters argue that U.S. involvement in the war -- across presidents from both parties and without explicit congressional authorization -- is unconstitutional, has killed tens of thousands, and supports the mission of a nation which does not share American values.
"This is the culmination of several years of legislative efforts to end our involvement in the Saudi war in Yemen," Rep. Khanna said in a press release. "I'm encouraged by the direction people are pushing our party to take on foreign policy, promoting restraint and human rights and with the sense they want Congress to play a much larger role."
"Together, we will work to end the worst humanitarian crisis of our time by ending all U.S. involvement in the Saudi-led war in Yemen," Khanna said in another press release.
What opponents say
Opponents counter that continued U.S. military involvement in Yemen serves our national interests, and would make it more likely for a peace settlement to be reached sooner rather than later.
"The most important thing remains the ability to apply direct pressure to Al Qaeda on the Arabian Peninsula and to ISIS on the Arabian Peninsula," said Lt. Gen. Kenneth McKenzie, the president's nominee for U.S. Central Command Commander. "We should all remember that before 2001, an attack against a U.S. warship initiated by AQAP was actually one of the early attacks of this long war that we're in."
"So they have an aspiration to attack the United States. They are prevented from doing that only because of the direct pressure that remains on them. That is a clear, unequivocal national interest of the United States."
Odds of passage
The resolution first attracted 96 bipartisan House cosponsors: 93 Democrats and three Republicans.
It then passed on February 13 by a 248-177 vote, with Democrats unanimously in favor 230-0 and Republicans largely opposed 18-177.
The few Republicans who did vote in favor were largely Freedom Caucus or Liberty Caucus members, who tend to be some of the president's most ardent supporters, but also more isolationist and against military involvement in foreign nations than other Republicans. Here's what one Republican who voted in favor argued:
"Many Americans do not embrace the unconstitutional and costly status quo of American-funded and American-operated perpetual combat around the world," Rep. Warren Davidson (R-OH8) said in a press release. "The idea that it is wrong to secure our own borders, but right to fight for someone else's sovereignty is appalling."
"Congress needs to reclaim its Article One war-making authority," Rep. Davidson continued. "The military should not be used to engage in unauthorized wars or conduct operations, for which a clear mission has not been articulated and approved by Congress."
Possible next steps
It now goes to the Senate, where a December 2018 vote in the previous Congress passed 56-41, but never receive a vote in the then-Republican House. Senate Democrats unanimously supported it 47-0, while Republicans largely opposed 7-41.
If the Senate passes the current version as well, it will be the first time that both the House and Senate adopt a War Powers resolution. Advocates hope this could herald a new era when the legislative branch begins reassuming more decision-making on military matters, which it had by and large ceded to the executive branch in recent decades.
Even though Senate Majority Leader Mitch McConnell (R-KY) opposes the measure and is able to prevent most legislation from even reaching the Senate floor if he wants, under Senate rules this is different -- it can receive a vote without McConnell's go-ahead. The International Security and Arms Export Control Act of 1976 requires that the Senate version be brought to the floor one way or another.