WASHINGTON ― A slim majority of senators voted Thursday to end U.S. support for a Saudi Arabian military campaign in Yemen that has been blamed for tens of thousands of deaths and mass starvation. The vote provides the biggest rebuke yet of a three-year U.S. policy that the Trump administration says it has no plans to end.

The historic 56-41 vote on a resolution from Sens. Bernie Sanders (I-Vt.), Chris Murphy (D-Conn.) and Mike Lee (R-Utah) represents the first time the Senate has voted to end a U.S. military operation not approved by Congress. It’s also a major loss for the Saudis, who are already worried about mounting criticism in Washington over their government’s role in the murder of Washington Post columnist Jamal Khashoggi.

But the passage of the resolution is symbolic, at least for the moment. It will not legally require President Donald Trump to withdraw American intelligence and logistical assistance for the Saudi effort because the GOP has quashed attempts to pass similar bills in the House this session and, even if passage there was possible, Trump has already threatened to veto the resolution.

“Today is the beginning of a new day in terms of the Congress acting on military issues,” Sanders said after the vote, adding that it is important for the public to see that “their elected representatives are about to take back their constitutional responsibility on the issues of war.”

Because the resolution was considered “privileged” under the 1973 War Powers Act, which limits military actions abroad without a formal congressional declaration of war, senators were able to force a vote on it after an initial attempt to bring it up failed in March. Since then, outrage over the Khashoggi killing, fresh accusations of war crimes by the Saudis and their partners in Yemen and fierce advocacy have helped the bill’s advocates rack up significant new support. They won over 10 Democrats ― all 49 voted for the legislation this time around ― and in an earlier vote on whether the Senate should take up the proposal, dramatically secured 14 Republican votes. Only two GOP members, Lee and his ally Sen. Rand Paul (R-Ky.), ultimately stood by the bill. Senate Majority Leader Mitch McConnell (R-Ky.) loudly condemned it, warning that it could help Iran, which is supporting the Yemeni rebel group that the Saudis are fighting.

CIA Director Gina Haspel helped stiffen senators’ resolve to admonish the kingdom in a briefing last week in which she offered details of a classified CIA assessment that blames de facto Saudi ruler Crown Prince Mohammed bin Salman for the Khashoggi assassination, undercutting Trump’s claims that the crown prince might not have been involved.

The fact that a U.S.-made bomb killed dozens of children in a Yemen school bus in August also helped convince several Democrats who previously opposed ending the policy to change their minds, according to Murphy.

“I think this resolution was going to pass even if Khashoggi was never murdered. I think the momentum was just growing,” Murphy told reporters Wednesday.

Senators faced uncharted territory in forcing a vote to curtail the president’s war-making powers, including the possibility of unlimited amendments that threatened to kill the effort once more. The resolution’s proponents successfully sidestepped the procedural hurdles via a parliamentary procedure on the floor, however, limiting debate to only a handful of amendments.

One of those amendments, authored by Sen. Todd Young (R-Ind.), would codify Trump’s decision to end one crucial part of the U.S. support: the aerial refueling of jets belonging to the Saudis and their partners the United Arab Emirates. It was adopted Thursday by a vote of 58-41.

The Senate on Thursday also unanimously approved a nonbinding joint resolution authored by Senate Foreign Relations Chairman Bob Corker (R-Tenn.) that directly blames Saudi Crown Prince Mohammed bin Salman for Khashoggi’s murder and calls for a ceasefire to hostilities in Yemen. It was backed by GOP leadership and other hawks in the Senate, who opposed ending U.S. support for the Saudis.

The Pentagon admitted this week that “errors in accounting” meant the Saudis and Emiratis have not been properly charged for that refueling assistance.

“It’s a fraud,” Murphy said Wednesday of the revelation. “The American taxpayers were told they weren’t going to foot the bill for this, and they have been. These are hundreds of billions of dollars we’re spending to refuel planes that are hitting school buses. That’s an abomination.”

Activists supporting the bill described their win this week as a seminal moment and evidence that grassroots pressure over the crisis in Yemen and over Saudi excesses more broadly would force even greater upheavals in the traditionally chummy U.S. relationship with the autocratic kingdom.

Still, additional action on Yemen, where humanitarian groups warn millions may soon slip into famine status, is unlikely on Capitol Hill this year. With many in Washington expecting the Senate vote to go as it did, the GOP-controlled House moved preemptively and used a controversial provision in a must-pass spending bill to block the House from considering any version of the Yemen bill this session, making it harder to amplify the congressional condemnation.

Rep. Thomas Massie (R-Ky.) on Wednesday expressed disappointment over the move, which was supported by five House Democrats.

By a vote of 206 to 203 congress just flushed our War Powers down the toilet. SAD! — Thomas Massie (@RepThomasMassie) December 12, 2018

What observers of U.S.-Saudi relationship and the potential for any improvement in Yemen will now be monitoring is how the White House and Riyadh react to the growing pressure. The hope among backers of the Yemen bill and outside peace groups is that the signal from the Senate will at least compel the Saudi-led coalition to hold off on a planned assault on the critical port city of Hodeidah and get more serious about ongoing peace talks with the Iran-backed rebels.