A Yemeni child recites a prayer by the graves of schoolboys who were killed while on a bus that was hit by a Saudi-led coalition air strike, at a cemetery in Saada on September 4, 2018. Photo: STRINGER/AFP/Getty Images

In an unusual show of unity, on Thursday the Senate voted 56-to-41 to end U.S. involvement in the Saudi-led war in Yemen, then voted unanimously to condemn Crown Prince Mohammed bin Salman for the killing of journalist Jamal Khashoggi. The Yemen resolution — written by Republican senator Mike Lee and Independent senator Bernie Sanders — was a rare invocation of the 1973 War Powers Act, and the most significant rebuke of President Trump’s refusal to cast blame on MBS and the Saudis. The move will not have an immediate effect on the war in Yemen, which has killed thousands of civilians and created a famine, but it contains several harbingers for the year ahead.

The bipartisan consensus on Middle East policy is fading fast.

For decades, even after 9/11, leaders in both parties have ignored public distaste for some of Saudi Arabia’s policies, and for the alliance itself. The killing and dismemberment of Khashoggi connected that public distaste with the growing concern felt by foreign policy elites over Mohammed bin Salman’s policies — and President Trump’s apparent willingness to tie all U.S. goals in the Middle East to MBS. A number of foreign policy moderates who had opposed the Senate measure earlier this year supported it this time, and think-tank leaders who have spent years working with the Saudis applauded it. This week, two Obama administration veterans called on Washington to begin pulling back from what they called the “purgatory” of Washington’s overcommitment to Middle Eastern regimes whose behavior it cannot limit. It appears that a number of prominent Republicans quietly agree.

The fight to end U.S. involvement in Yemen isn’t going away — and neither is the war.

The fact that seven Republicans — Mike Lee, Susan Collins, Steve Daines, Jeff Flake, Jerry Moran, Rand Paul, and Todd Young — joined all Democrats in voting for an end to U.S. involvement in the war in Yemen suggests that the bill will have a decent chance of passing again in the next Congress. Why does that matter? Although a similar bill easily passed the House earlier this year (with support from Democrats and tea party Republicans), House Speaker Paul Ryan and the GOP leadership used procedural tricks to ensure such a measure could not come to the floor in the waning days of this year. Unless Ryan backs down next week, that means the Senate measure to end U.S. support for the war cannot become law. With a new Congress in January, everything starts over — but presumably the measure would again pass easily in a Democrat-controlled House.

Meanwhile, a round of U.N.-sponsored Yemen peace talks in Sweden wrapped up on Thursday, offering a tiny sliver of hope that progress could be made toward ending the violence and improving civilian access to food and health care. But no one thinks that the conflict can be brought to a quick close — before, say, Congress reconvenes and takes the issue up again. Tragically, for now, millions of Yemenis will remain at risk of death from starvation, disease, and violence.

Transpartisanship — or the politics of strange bedfellows — may be on the rise.

The Senate resolutions passed as senators struggled to advance another measure whose origins lie in partnership between the activist left and libertarian right: criminal-justice reform. The First Step Act would loosen some of the rules governing how federal courts treat drug and other crimes, and provide more avenues to prisoner rehabilitation. It is a small subset of the changes to how crimes are prosecuted and punished that reformers have rolled out around the country — including in some of the reddest states. In both cases, success relied on alliances between progressive and libertarian activists, which eventually brought around congressional Democrats and one wing of the GOP. While neither alliance has yet produced a definitive policy outcome at the federal level, expect to see more of them — on issues from defense spending to climate change.

Congress may finally have a real debate about where and how the U.S. uses force.

Speaking of cross-partisan alliances, some of the same senators and activists who labored for months to bring the Yemen bill to a vote also share a broader interest in debating, and limiting, the many places where the U.S. is engaged in military operations. Bizarrely, they point out, the authorization for the use of force passed by Congress in the immediate aftermath of 9/11 is still used to justify military operations from West Africa to Central Asia, the majority of which target groups which are not Al Qaeda or the Taliban, and didn’t even exist on 9/11 (as in the case of ISIS).

This debate can very quickly get bogged down in the finer points of constitutional law. What counts as “use of military force”? Who are the successors to Al Qaeda? How much say should Congress have over the use of small numbers of troops, or of drones? And then there’s politics to consider: Who takes the blame if an operation goes wrong or, as in the run-up to 9/11, if an emerging threat is ignored?

Still, Congress’s willingness to challenge not just Trump but also Defense Secretary James Mattis and Secretary of State Mike Pompeo on Yemen, and to invoke the rarely used War Powers Act to do so, suggests that we may be edging toward a new era of, if not congressional activism on national security, at least congressional engagement. There is precedent for this: The War Powers Act itself is part of the last great set of congressional security oversight reforms, which came about in the 1970s, as lawmakers were questioning the president’s foreign policy moves and mulling his potential impeachment.