President Trump has vetoed a bill Congress passed to end U.S. military assistance in the Saudi Arabia-led war in Yemen. In a break with the president, Congress voted for the first time to invoke the war powers resolution to try and stop U.S. involvement in a foreign conflict.

Mr. Trump vetoed the measure Tuesday. Congress lacks the votes to override him. "This resolution is an unnecessary, dangerous attempt to weaken my constitutional authorities, endangering the lives of American citizens and brave service members, both today and in the future," Mr. Trump wrote in explaining his veto.

Congress has grown uneasy with the president's close relationship with Saudi Arabia as he tries to further isolate Iran, a regional rival. Many lawmakers also criticized the president for not condemning Saudi Arabia for the killing of a Saudi writer Jamal Khashoggi, a Saudi who lived in the United States and had written critically about the kingdom. Khashoggi went into the Saudi consulate in Istanbul last October and never came out. Intelligence agencies said Saudi Crown Prince Mohammed bin Salman was complicit in the killing.

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The ongoing civil war has caused one of the biggest humanitarian crisis on the planet. According to the United Nations, a quarter of a million Yemenis have been facing starvation.

House approval of the resolution came earlier this month on a 247-175 vote. The Senate vote last month was 54-46.

Democratic Rep. Eliot Engel of New York, chairman of the House Foreign Affairs Committee, voted to end U.S. military assistance to the war, saying the humanitarian crisis in Yemen triggered "demands moral leadership."

Sen. Tim Kaine, D-Virginia, said that Mr. Trump's veto "shows the world he is determined to keep aiding a Saudi-backed war that has killed thousands of civilians and pushed millions more to the brink of starvation."

Kaine accused Mr. Trump of turning a blind eye to Khashoggi's killing and the jailing of women's rights activists in Saudi Arabia. "I hope my colleagues will show we won't tolerate the Trump administration's deference to Saudi Arabia at the expense of American security interests by voting to override this veto," Kaine said.

The top Republican on the committee, Rep. Michael McCaul of Texas, acknowledged the dire situation in Yemen for civilians, but spoke out in opposition to the bill. McCaul said it was an abuse of the war powers resolution and predicted it could disrupt U.S. security cooperation agreements with more than 100 countries.

Mr. Trump issued his first veto last month on legislation related to immigration. Mr. Trump had declared a national emergency so he could use more money to construct a border wall. Congress voted to block the emergency declaration and Trump vetoed that measure.