The US President said the resolution "endangered the lives of American citizens" (Picture: PA).
US President Donald Trump has vetoed a resolution passed by Congress that would have ended US support for the Saudi-led coalition in the conflict in Yemen.
The veto - the second in President Trump's term in office - was expected, and Congress lacks the votes to override it.
President Trump described the resolution as "an unnecessary and dangerous" attempt to weaken his constitutional powers, "endangering the lives of American citizens and brave service members".
Congress has grown uneasy with President Trump's close relationship with Saudi Arabia as he tries to further isolate Iran, a regional rival.
The fighting between Iran-backed Houthi rebels and a Saudi-led coalition in support of the internationally-recognised government of Yemen continues after a breakdown in peace talks.
The US provides billions of dollars of arms to Saudi Arabia.
Likewise, the UK also provides arms to the Saudi-led coalition.
Members of Congress have expressed concern about the thousands of civilians reportedly killed in coalition air strikes since the conflict began in 2014.
The fighting in Yemen has left millions suffering from food and medical care shortages, pushing the country to the brink of famine.
President Trump said the measure was unnecessary because except for counterterrorism operations against so-called Islamic State militants and al-Qaida in the Arabian Peninsula, the US is not engaged in hostilities in or affecting Yemen.
He added there were no US military personnel in Yemen accompanying the Saudi-led coalition.
However, he acknowledged the US has provided limited support to the coalition, including intelligence sharing and logistics support.
President Trump said the US is providing the support to protect the safety of more than 80,000 Americans who live in certain areas of the coalition countries subject to Houthi attacks from Yemen.
Democratic Representative Eliot Engel, chairman of the House Foreign Affairs Committee, voted to end US military assistance to the war, saying the humanitarian crisis in Yemen triggered "demands moral leadership".
Supporters of the War Powers Resolution had argued that the US shouldn't be involved in any war without explicit permission from Congress.