The United States military early Thursday launched the Tomahawk cruise missiles targeting three coastal radar sites in the rebel Houthi-controlled areas of Yemen, following the firing of missiles on a U.S. Navy destroyer earlier this week.

The strikes were carried out around 4 a.m. local time (9 p.m. EDT Wednesday) after the Pentagon said it would retaliate to the firing of a pair of missiles at the Navy destroyer USS Mason on Wednesday while it was in international waters close to the Bab el-Mandeb Strait.

The strikes were authorized by U.S. President Barack Obama on the recommendation of Secretary of Defense Ash Carter and Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford, Pentagon Press Secretary Peter Cook said in a statement.

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

Reuters reported U.S. officials, speaking on condition of anonymity, saying that U.S. Navy destroyer USS Nitze launched the Tomahawk cruise missiles. An official said the Yemeni areas targeted were near Ras Isa, north of Mukha, and near Khoka along the country’s western coastline.

Since the civil war between Shiite Houthi rebels and the government of President Abed Rabbo Mansour Hadi broke out in March 2015, at least 4,125 civilians have been killed in the country,  the office of the U.N. High Commissioner for Human Rights said Monday. It also said that an agreement to cease hostilities between the two sides collapsed in August.

Saudi Arabia, a close ally of the U.S. and a supporter of the Yemeni government, has accused Iran of backing the Houthi rebels. An airstrike by the Saudi-led coalition reportedly killed 140 people at a funeral hall Saturday. The strikes on the U.S. naval vessels were possibly a response to the Saturday attack, according to reports.