WASHINGTON — The U.S. is weighing what military response it should take against Yemen-based Houthi rebels, who U.S. officials say launched two missiles at American warships in the Red Sea on Sunday, the Pentagon said Tuesday.

Navy Capt. Jeff Davis, a Pentagon spokesman, said the U.S. is still investigating the unprecedented incident, including the exact location of the missile launches. Asked if the U.S. was developing targets for a possible retaliatory strike, he said he could not confirm that.

“Those things are things that we’re looking at,” Davis told Pentagon reporters. “We want very much to get to the bottom of what happened. We’re going to find out who did this and we’ll take action accordingly.”

He added that “we will make sure that anybody who interferes with freedom of navigation or anybody who puts U.S. Navy ships at risk understands that they do so at their own peril.”

U.S. officials believe Iranian-backed Shiite rebels, known as Houthis, launched variants of the so-called Silkworm missile at the USS Mason and the USS Ponce. Both missiles fell harmlessly into the water. The Silkworm is a type of coastal defense cruise missile that Iran has been known to use.

Davis said the missiles were fired from Houthi-held territory on the Yemen coast.

This was the first time that U.S. ships were targeted by a missile launch from Yemen. Last week, an Emirati-leased Swift boat came under rocket fire near the same area and sustained serious damage. The United Arab Emirates described the vessel as carrying humanitarian aid and having a crew of civilians, while the Houthis called the boat a warship.

Davis said the commander of the USS Mason, an Arleigh Burke class of guided missile destroyer, believed the initial missile was a threat to his ship or to the USS Ponce, an amphibious warship accompanying the USS Mason. The USS Mason took defensive action against the first missile, but Davis would not say exactly what countermeasure or weapon was used.

It wasn’t clear if the ship’s defensive attack took down the missile or if it simply fell into the water. The second missile fell into the water before any countermeasures were used.

Davis said the USS Mason didn’t launch a counteroffensive against the Houthis, but he would not go into a detailed explanation, saying that military rules of engagement are classified. The U.S., however, requires significant analysis before launching strikes on a location where there could be innocent civilians.

The Houthi-controlled SABA news agency of Yemen quoted an anonymous army official denying its forces fired on the USS Mason, without elaborating.

The missile attacks came on the heels of two other attacks against Saudi sites. A ballistic missile fired from Yemen apparently targeted a Saudi air base near the Muslim holy city of Mecca, the deepest strike yet into the kingdom by Shiite rebels and their allies. The rebels fired another two missiles into the Saudi Jizan region along the border on Monday, wounding two foreigners who worked there, the local civil defense said in a statement.

The Houthis and their allies have 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.

The deliberations about how to retaliate to the missile launches come as the U.S. considers withdrawing its support for the Saudi-led coalition fighting the Houthis following Saturday’s airstrike on the funeral and other troubling incidents of civilian casualties as a result of the Saudi bombing campaign.

Human rights groups have expressed outrage over the deaths and accused the U.S. of complicity, leading the White House to say it was conducting a “review” to ensure U.S. cooperation with longtime partner Saudi Arabia is in line with “U.S. principles, values and interests.”

Associated Press writers Jon Gambrell and Josh Lederman contributed to this report.