WASHINGTON — The Senate voted resoundingly on Thursday to withdraw American military assistance for Saudi Arabia’s war in Yemen, issuing the latest in a series of stinging bipartisan rebukes of President Trump for his defense of the kingdom amid outrage in both parties over Riyadh’s role in the killing of a dissident journalist.
The 56-to-41 vote was a rare move by the Senate to limit presidential war powers and send a potent message of official disapproval for a nearly four-year conflict that has killed thousands of civilians and brought famine to Yemen. Its immediate effect was largely symbolic, after the House earlier this week moved to scuttle it, all but assuring that the measure will expire this year without making it to Mr. Trump’s desk.
But the action signaled a growing sense of urgency among lawmakers in both parties to punish Saudi Arabia for its role in the brutal killing of the journalist Jamal Khashoggi, and to question a decades-old bipartisan tradition of Washington averting its gaze from human rights abuses and other wrongdoing by the kingdom in the interest of preserving a strategically important relationship in the Middle East.
Senators also approved, by a voice vote, a resolution to hold Crown Prince Mohammed bin Salman, the heir to the kingdom’s throne, personally responsible for Mr. Khashoggi’s killing. The nonbinding measure also calls on Saudi Arabia to “moderate its increasingly erratic foreign policy” and urges an end to American air-to-air refueling of bombers operating in Yemen.
Mr. Trump dug in on that position on Tuesday in an interview with Reuters, saying he was standing by Prince Mohammed despite the C.I.A.’s findings, and saying the crown prince was “very strongly in power” in Saudi Arabia.
“I absolutely believe that if the crown prince came before a jury here in the United States of America, he would be convicted guilty in under 30 minutes,” Senator Bob Corker, a Tennessee Republican who heads the Foreign Relations Committee, said on the Senate floor on Wednesday. “I absolutely believe he directed it. I believe he monitored it. And I believe he is responsible for it.”
Senators in both parties described the measures as direct responses to the refusal by Mr. Trump and his administration to hold Saudi Arabia to account for Mr. Khashoggi’s death, and a way to counter the president’s own statements that the money to be made from arms sales to the kingdom was enough to justify turning a blind eye to such a deed.
“We cannot sweep under the rug the callous disregard for human life and flagrant violations of international norms the Saudis are showing,” said Senator Robert Menendez of New Jersey, the senior Democrat on the Foreign Relations Committee.
“Saudi Arabia has joined a sinister clique along with North Korea, Russia and Iran in its assassination of Jamal Khashoggi,” Mr. Menendez said. “A few more weapons purchases cannot buy our silence. It should not buy our silence, and if the president will not, Congress must act.”
The votes came only hours after Defense Secretary Jim Mattis and Secretary of State Mike Pompeo implored members of the House of Representatives during a closed-door briefing to continue the military advising, logistics support and intelligence that have for years been shared with Saudi Arabia.
Some lawmakers emerged from the House meeting frustrated that Mr. Pompeo and Mr. Mattis had defended the United States’ relationship with the kingdom, which the White House needs to counter growing Iranian influence in the Middle East.
Representative David Cicilline, Democrat of Rhode Island, said the two top administration officials had warned against jeopardizing the Saudi partnership — given what they described as a continuing, open investigation into whether Prince Mohammed had, in fact, ordered the killing of Mr. Khashoggi, a Washington Post columnist who had lived in the United States.
“The briefing was a colossal waste of time,” Mr. Cicilline told reporters afterward.
Some senior Republicans offered the administration officials more support.
Representative Steve Scalise of Louisiana, the No. 3 Republican in the House, said Mr. Pompeo and Mr. Mattis had explained details of the investigation into Mr. Khashoggi’s death, as well as complexities of the relationship with Saudi Arabia.
“There needs to be action,” Mr. Scalise said, without elaborating. “We need to hold everyone accountable.”
Mr. Mattis and Mr. Pompeo gave a similar briefing to the Senate late last month. But it broke down as Republican and Democratic senators alike grew irritated with the administration’s defense of Prince Mohammed.
Gina Haspel, the C.I.A. director, briefed senior House members on Wednesday, and lawmakers have said little about it since they left the closed meeting. Her appearance, ahead of Thursday’s briefing, seemed to defuse much of the anger the administration officials faced in their briefings to the Senate in late November to senators. By contrast, senators said they were even more convinced of Price Mohammed’s role after hearing from her last week.
Mr. Pompeo slipped out of the Capitol after Thursday’s meeting without speaking to journalists; he had vigorously defended the administration’s position to reporters and TV cameras after briefing the Senate.
The measure limiting war powers in Yemen has been under consideration for months, but senators sharpened its language two weeks ago with a procedural vote that signaled their deep frustration over the Trump administration’s refusal to blame Prince Mohammed for Mr. Khashoggi’s killing.
“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,” Senator Lindsey Graham, Republican of South Carolina, told reporters on Wednesday.
But Mr. Graham and other senators sought to separate the importance of maintaining a close alliance and partnership with Saudi Arabia, and punishing Prince Mohammed.
Before the killing and dismemberment of Mr. Khashoggi, most Republicans had supported the military alliance between the United States and Saudi Arabia.
But in the Saudi-led campaign in Yemen, to which the Pentagon has supplied bombs and intelligence, Saudi airstrikes targeting Houthi rebels have also killed thousands of people at weddings, funerals and on school buses.
In late October, Mr. Mattis and Mr. Pompeo had called for a cease-fire in Yemen, and on Thursday, talks that were brokered by the United Nations in Sweden appeared to reach an agreement to ease the hostilities.
The agreement calls for an exchange of up to 15,000 prisoners, the creation of a humanitarian corridor into the city of Taiz and, importantly, the withdrawal of troops from Hudaydah. That city, on the Red Sea, is a key entry point to Yemen for essential products like food and medicine.
Peace talks are expected to continue in January in an effort to resolve what has become a humanitarian crisis in one of the poorest nations on Earth.
“The agreements today mean a lot, not only for the Yemeni people but for humanity if this can be a starting point for peace and for ending the humanitarian crisis in Yemen,” António Guterres, the United Nations secretary general, said at the close of the talks on Thursday.
Mr. Menendez and Mr. Graham said on Wednesday that they, and other senators, would introduce legislation early next year to impose even broader penalties against Saudi Arabia, including suspending weapons sales and cementing a ban on American refueling of Saudi coalition aircraft in Yemen.
Additionally, their plan would impose economic sanctions against people who are found responsible for Mr. Khashoggi’s death, who blocked humanitarian relief in Yemen or who supported the Houthi rebels.
While Thursday’s moves were largely a symbolic, if stinging, slap at the Trump administration, they previewed what could be a far more consequential debate after Democrats take over the House in 2019.
“If Paul Ryan thinks on his way out the door his last public service gift to humanity is covering up for Saudi Arabia, great, he can make that his legacy,” said Senator Tim Kaine, Democrat of Virginia, referring to the procedural gambit by Mr. Ryan, the House speaker, this week to block the war powers measure from a vote.
“But we’re going to be around next year,” Mr. Kaine said, “and we’ll figure out ways that there can be consequences for this.”
An earlier version of this article misspelled the surname of the United Nations secretary-general. He is António Guterres, not Guterrez.
Eileen Sullivan and Gardiner Harris contributed reporting.