But the US national security adviser said he could not explain how a journalist was added to a chat discussing air strikes in Yemen.

President Trump also defended his national security team after a reporter was added to their message thread.

A National Security Council spokesman said in a statement the reported chat "appears to be authentic"

The Signal messages show the inner workings of the president's team and how his Vice-President JD Vance disagreed with him.

The US president says Iran's leadership would be blamed for "every shot fired by the Houthis".

The US said it launched a "decisive and powerful" wave of air strikes on Houthi targets on Saturday.

Humanitarian workers fear the detention of staff and cuts in funding will be a "death sentence" for Yemenis.

The Yemeni man was one of seven UN staff held by Houthi authorities since late January.