The United States and Iran-backed Houthi rebels in Yemen are both vowing escalation after the U.S. launched airstrikes to deter the rebels from attacking military and commercial vessels on one of the world's busiest shipping corridors.

The U.S. carried out new airstrikes on Yemen, expanding the biggest U.S. military operation in the Middle East since President Trump took office.

President Trump says he has ordered a “decisive” military action against Houthi rebels in Yemen, opening a new salvo against the Iran-backed group that has targeted shipping lanes in the Red Sea.

The Iranian-backed rebels, who have targeted Israel and shipping in the Red Sea, said children were among those killed in the strikes ordered by President Trump.

Houthi leader Abdul Malik al-Houthi said his militants would continue to target American ships in the Red Sea as long as the U.S. attacks Yemen, warning, 'If they continue their aggression, we will continue the escalation.