By Phil Stewart and Idrees Ali

WASHINGTON (Reuters) - The Pentagon declined to say on Monday whether the USS Mason destroyer was targeted by multiple inbound missiles fired from Yemen on Saturday, as initially thought, saying a review was under way to determine what happened.

Any determination that the USS Mason guided-missile destroyer was targeted on Saturday could have military repercussions, since the United States has threatened to retaliate again should its ships come under fire from territory in Yemen controlled by Iran-aligned Houthi fighters.

The United States carried out cruise missile strikes against radar sites in Yemen on Thursday after two confirmed attempts last week to hit the USS Mason with coastal cruise missiles.

"We are still assessing the situation. There are still some aspects to this that we are trying to clarify for ourselves given the threat - the potential threat - to our people," Pentagon spokesman Peter Cook told a news briefing.

Admiral John Richardson, the chief of naval operations, disclosed the latest incident during an event in Baltimore on Saturday, saying the USS Mason "once again appears to have come under attack in the Red Sea."

Cook noted that the crew aboard the USS Mason detected what appeared to be a missile threat and responded appropriately.

U.S. officials cautioned, however, that details from the incident were still under review. It was unclear how soon a final determination might be made about how many, if any, missiles were actually fired at the USS Mason.

The U.S. cruise missiles launched on Thursday knocked out three coastal radar sites in areas of Yemen controlled by Houthi forces, in Washington's first direct military action against suspected Houthi-controlled targets in Yemen's conflict.

BACKLASH TO SAUDI-LED CAMPAIGN

Since March 2015, Yemen has been gripped by war pitting the Houthi group, backed by troops loyal to former President Ali Abdullah Saleh, and the internationally recognized government of Abd Rabbu Mansour al-Hadi, backed by Saudi Arabia.

The Houthi movement has denied firing on the ship. But it did promise to retaliate after a Saudi-led strike on a funeral gathered in Yemen's Houthi-held capital Sanaa last week, killing 140 people according to one U.N. estimate, and 82 according to the Houthis.

Although the United States has condemned the strike and promised to review U.S. military assistance to the Saudi-led coalition battling in Yemen, the U.S. military has been closely associated with the campaign in the eyes of Yemenis.

The United States has regularly refueled Saudi jets participating in the Yemen campaign and has sold many of the munitions dropped on Yemeni targets, to name only two examples.

An investigative body set up by the Saudi-led coalition on Saturday blamed a series of factors for the funeral strike, including receiving incorrect information from Yemeni military figures that armed Houthi leaders were in the area at the time.

Rep. Ted Lieu, a Democrat from California and a leading advocate in Congress for a suspension in U.S. cooperation with the Saudi-led coalition, said that explanation sounded to him like an admission of a war crime.

"Even if some rebels had been present, that would not justify an air strike that targeted more than 600 civilians," he told Reuters, referring to the size of the gathering.

Lieu, who taught classes on the law of war when he was a lawyer in the U.S. Air Force, said officials in Saudi Arabia responsible for the strike needed to resign and be investigated.

"The U.S. also needs to immediately cease aiding and abetting a Saudi coalition that has committed war crimes," he said.

The United Nations estimates that 10,000 people have been killed in the war and blames coalition air strikes for 60 percent of some 3,800 civilian deaths since March 2015.

(Reporting by Idrees Ali and Phil Stewart; Editing by Lisa Shumaker, Peter Cooney and Bernard Orr)