President Joe Biden has said that US and British air strikes against Yemen’s Houthis were “defensive” and warned of further measures if the Iran-backed rebels keep attacking ships in the Red Sea, AFP reports.

Biden, who is seeking reelection in November, said the latest American military intervention in the region was necessary as the Houthi attacks would “endanger freedom of navigation in one of the world’s most vital waterways.”

“These attacks have endangered US personnel, civilian mariners, and our partners, jeopardised trade, and threatened freedom of navigation,” Biden said in a statement.

“I will not hesitate to direct further measures to protect our people and the free flow of international commerce as necessary,” the 81-year-old added.

The strikes followed an “unprecedented” spate of 27 Houthi attacks on ships in the busy international sea route “including the use of anti-ship ballistic missiles for the first time in history,” Biden said.