Iranian-backed Houthi rebels fired two missiles at a U.S. Navy destroyer operating off the coast of Yemen in the Red Sea on Sunday -- though neither missile hit the ship, the Pentagon said in a statement.

Though the American warship wasn't struck, the ship was definitely targeted, a U.S. defense official told Fox News. This dramatic escalation comes a week after the U.S. Navy sent warships to the area when a United Arab Emirates flagged auxiliary ship was destroyed off the coast of Yemen by the Houthis.

"We assess the missiles were launched from Houthi-controlled territory in Yemen," Pentagon spokesman Capt Jeff Davis said. "The United States remains committed to ensuring freedom of navigation everywhere in the world, and we will continue to take all necessary steps to ensure the safety of our ships and our servicemembers."

It was not immediately clear how close the missiles came to the destroyer.

"In the first instance USS Mason employed onboard defensive measures, although it is unclear whether this led to the missile striking the water or whether it would have struck the water anyway," a defense official told Fox News.

Officials said the American ship was conducting routine operations in international waters when the missiles were fired, but didn't provide an exact location.

"Beyond that, the incident is under investigation, and we hope to have more details for you in the coming days," the defense official said. "We take this very seriously. We will protect our people."

The White House condemned the missile firings, a senior administration official told Fox News.

U.S. officials have long accused Iran of supplying missiles and other weapons to the Houthis.

The U.S. supports a Saudi-led coalition in Yemen's civil war, which began in 2015. The U.S. embassy was closed in Yemen over a year ago.

Fox News first reported last week that U.S. warships were sent to Yemen's coast after a United Arab Emirates ship was recently targeted by the Houthis. That ship used to be owned by a U.S. company, but was contracted to UAE at the time.

Yemen's Shiite rebels and their allies offered no reason for the launches, though they came after a Saudi-led airstrike targeting a funeral in Yemen's capital killed more than 140 people and wounded 525 on Saturday.

Fox News' Kristin Brown and The Associated Press contributed to this report.

Lucas Tomlinson is the Pentagon and State Department producer for Fox News Channel. You can follow him on Twitter: @LucasFoxNews