President Donald Trump is overriding Congress on a measure that would have ended U.S. involvement in the Yemen war.

Trump said Tuesday (April 16) he's vetoing the bill, which was passed in both houses of Congress earlier this year.

Yemen is on the brink of famine, after a civil-war that's now stretched into its fourth year.

The resolution was the first time in U.S. history both the House and Senate had supported the so-called War Powers resolution.

That can limit the president's power to send troops into action.

In his veto message, Trump accused Congress of trying to weaken his constitutional authority.

Adding that the resolution to curb U.S. support for the war, is unnecessary and endangers the lives of American citizens and service members.

It's now the second time Trump has used his veto card since coming into office.

The civil-war pits the Saudi-led coalition, against rebels backed by Iran.

The U.S. doesn't provide soldiers on the ground, but it has helped its allies in Saudi Arabia, with measures including arms sales and targeting support for Saudi airstrikes.

Supporters of the U.S. involvement there argue a withdrawal could give a boost to the Iran-linked Houthi rebels.

The United Nations calls the war the world's most dire humanitarian crisis that's killed tens of thousands of people.