"This resolution is an unnecessary, unsafe attempt to weaken my constitutional authorities, endangering the lives of American citizens and fearless service members, both today and in the future", Trump wrote in explaining his veto. The Trump administration also argued that US activities in support of Saudi-led forces did not constitute "hostilities" and claimed the resolution could "establish bad precedent for future legislation".
No one was surprised by the veto - had Trump wanted to comply with the resolution, he could have withdrawn support to Saudi Arabia at any time.
The bill passed the House 247-175. Trump argued that USA support for the bloody war between the Saudi-backed Yemeni government and Iran-aligned Huthi rebels was necessary for a variety of reasons, "first and foremost" to "protect the safety of the more than 80,000 Americans who reside in certain coalition countries".
"Coalition continues to work without interruption to support peace through United Nations led Stockholm Agreement & its commitment to the humanitarian & political dimensions of the Yemen crisis unshakable".
House Speaker Nancy Pelosi denounced Trump's veto, saying it would serve to "perpetuate America's shameful involvement in this heartbreaking crisis".
Iran-backed Houthi rebels have been accused of acts that could amount to war crimes and regularly fire drones at Saudi cities.
Pelosi added: "This conflict must end, now".
"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", he said.
The top Republican on the House Foreign Affairs Committee, Rep. Michael McCaul of Texas, acknowledged the dire situation in Yemen for civilians, but spoke out in opposition to the measure when it was passed.
The U.S. has provided intelligence and logistical support to the Saudis since 2015.
Sen. Sanders has led the charge on the Yemen resolution and might make this a larger fixture of his 2020 presidential campaign, now that the president vetoed the resolution. Vetoing the measure is an "effective green light for the war strategy that has created the world's worst humanitarian crisis to continue", said International Rescue Committee president and CEO David Miliband.
Trump used his first veto in March to shut down a bipartisan resolution condemning his declaration of a national emergency to secure funding for a southern border wall.