(Lobelog) The Senate on Wednesday passed a measure mandating the withdrawal of U.S. forces from the Saudi/UAE-led war against Houthi rebels in Yemen. The vote marks the first time since the War Powers Act of 1973 became law that both chambers of Congress have directed the president to withdraw American forces from a conflict.

This is a big deal.

The U.S. role in this needlessly destructive war is unlikely to end any time soon. Donald Trump, who appears to have a special fealty to the Saudi leadership and its criminal activity, has said that he will veto the resolution. But U.S. withdrawal is only a matter of time—that is, a matter of Trump’s time in office.

Indeed, one important feature of this vote is that Congress—with the help and prodding of grassroots activists—has officially normalized a policy of withdrawal from the Yemen war on a bipartisan basis.

At the same time, the vote also has wider implications for U.S. foreign policy outside of ending the war in Yemen. It has put a serious crack in the structure of U.S. foreign policy making. Since at least 9/11, U.S. foreign policy has been dominated by an executive branch run by leaders of both parties seemingly bent on expanding where and when the United States is involved in war, a status quo that allowed the Yemen war to continue without congressional authorization.

By cancelling the blank check in Yemen, Congress now has momentum to finally repeal the 2001 Authorization for the Use of Military Force (AUMF), which authorized the U.S. invasion of Afghanistan but has been used since to justify subsequent and unrelated wars. That process gained energy two years ago after a bipartisan majority in a House subcommittee passed a measure, sponsored by Rep. Barbara Lee (D-CA), that would have repealed the 2001 AUMF, only for the House GOP leadership to later strip the measure.

Lee has reintroduced a similar measure in this Congress, and a bipartisan repeal effort is now underway in the House. Meanwhile,  eight lawmakers —including rising stars Reps. Ilhan Omar (D-MN) and Alexandria Ocasio-Cortez (D-NY) and two Democratic presidential candidates Sens. Elizabeth Warren (D-MA) and Bernie Sanders (I-VT)—recently signed a separate pledge to “end the forever war.”

This week’s Senate vote on Yemen has also dented another staple of U.S. foreign policy: unwavering American support for the Saudi monarchy. Change in the U.S.-Saudi relationship is obviously due in large part to the murder of Washington Post columnist Jamal Khashoggi, which the CIA concluded with high confidence was ordered by Saudi Crown Prince Mohammed bin Salman. That change yielded a tangible outcome in a Senate vote to end U.S. support for the Yemen war late in the last Congress. A handful of Republicans back then offered their support for the measure—or at least wouldn’t block it from moving to a floor vote—because of their disgust with MbS and with the Trump administration for defending the Saudis and refusing to enact meaningful consequences for Khashoggi’s murder.

Ten years ago, it would have been unheard of for the Senate to issue such a sharp rebuke to Saudi Arabia. Less than two years ago, Sen. Lindsey Graham (R-SC) delivered an impassioned speech defending an arms deal with the Saudis. But now, his feelings have completely reversed. “The relationship with the crown prince is so toxic, so tainted, so flawed that I can’t ever see myself doing business with Saudi Arabia in the future unless there is change there,” he said in December.

But Khashoggi’s murder doesn’t account for all Republican defections. Both House and Senate measures garnered significant bipartisan support before it. Indeed, a lead sponsor of Wednesday’s Senate bill was Sen. Mike Lee (R-UT), and 18 Republicans in the House voted on a similar resolution last month. Referring to the fact that the Saudis and Emiratis are deliberately starving Yemenis, Sen. Todd Young (R-IN) said : “It offends my sensibilities—and I know it offends the sensibilities of all Americans—that there are countries in this day and age that are using food as a weapon of war.”

Largely overlooked throughout this whole process is that these votes show how U.S. foreign policy, so often a byproduct of Washington lobbyists and other powerful special interests, can be democratized. Saudi Arabia’s lobbyists did indeed mobilize to try to quash these votes, but their efforts fell far short, in large part because of a mass grassroots activist mobilization over the last few years pushing Congress to act. Rep. Ro Khanna (D-CA), the lead sponsor of the House measure to end support for the Yemen war, acknowledged the grassroots power on Yemen.

Win Without War, the Yemen Peace Project, the Friends Committee on National Legislation. They have all been instrumental. We would not have been able to do any of this without them. They’ve been instrumental in the drafting of the legislation. They’ve been instrumental in making sure members were aware of the legislation and convincing members to support the legislation.

Action on Yemen now shifts to the House, which already passed a resolution mandating U.S. withdrawal from the Saudi/UAE Yemen war. But due to procedural matters, the House must now vote again on either the Senate version that passed this week, or a reconciled version of the House and Senate bills.

Either way, U.S. support for the Saudi/UAE war in Yemen will end, and changes are coming to the way in which U.S. foreign policy is debated, enacted, and conducted.

Ben Armbruster is the communications director for Win Without War and previously served as national security editor at ThinkProgress.