The United States bombed three radar sites controlled by Huthi rebels in Yemen, the first direct US strike against the group following missile attacks against US warships last week, the Pentagon said.

The strikes in Huthi-controlled territory on Yemen's Red Sea coast, authorized by President Barack Obama, were conducted with Tomahawk cruise missiles fired by the destroyer USS Nitze, a US official said.

"Initial assessments show the sites were destroyed," Pentagon Press Secretary Peter Cook said in a statement.

The strikes "targeted radar sites involved in the recent missile launches threatening USS Mason and other vessels operating in international waters in the Red Sea and the Bab al-Mandeb," it added.

These limited self-defense strikes were conducted to protect our personnel, our ships, and our freedom of navigation in this important maritime passageway."

The USS Mason, a destroyer, was targeted on Wednesday. The missile fired from rebel-held territory crashed into the ocean before reaching its target. 

The Mason and the USS Ponce, an amphibious transport ship, were previously targeted on Sunday by two missiles that also fell short.

"The United States will respond to any further threat to our ships and commercial traffic, as appropriate, and will continue to maintain our freedom of navigation in the Red Sea, the Bab al-Mandeb, and elsewhere around the world," Cook said.

The United States is backing a Saudi-led coalition fighting the Iran-backed rebels and the forces of former Yemeni president Ali Abdallah Saleh.

But US air forces are not directly involved in strikes in Yemen, that are increasingly criticized by the international community for their devastating impact on civilians.

The Huthis swept into Sanaa in September 2014 and advanced across much of Yemen, forcing the government of President Abedrabbo Mansour Hadi to flee. 

The conflict has killed more than 6,700 people -- almost two-thirds of them civilians -- and displaced at least three million since the coalition launched military operations, according to the United Nations.

Source: AFP