Missile experts are questioning whether the Patriot missile defense system supplied by the United States to Saudi Arabia was responsible for shooting down a missile fired by Yemen’s Houthi rebel group last month.

The missile, which experts believe was a Burqan-2, traveled roughly 600 miles from Yemen and detonated near the King Khalid International Airport in Riyadh, Saudi Arabia. According to a United Nations report, evidence suggests Iran manufactured the missile.

After the missile was fired, President Trump and the Saudi defense ministry said the weapon had been successfully intercepted before hitting its target in Riyadh, the airport.

“I told you before, as you know, a missile was shot into Saudi Arabia recently, from Yemen, and one of our missile systems knocked it down,” Trump said Nov. 12 in remarks before a bilateral meeting in Vietnam. “Nobody even knew what happened, and the missile exploded in the air; knocked it down like nothing. We make the greatest missiles in the world, greatest planes in the world, greatest commercial aircraft in the world.”

But a team of analysts, led by Jeffrey Lewis of the Middlebury Institute of International Studies, analyzed photos and videos posted to social media and believe Saudi Arabia’s claim that the missile was shot down may be incorrect. They found evidence indicating the missile’s warhead may have flown past the missile defense unit, according to the New York Times.

The National Security Council did not return a request for comment.

Videos posted to social media show debris falling in downtown Riyadh after Saudi Arabia deployed its missile defenses, and Saudi officials said the debris indicated the missile defense system successfully intercepted the missile.

But according to the New York Times, which reviewed Lewis’s findings, the warhead component of the missile was missing from the rest of the debris, suggesting the Saudi defenses did not shoot down the missile.

Instead, researchers believe the missile broke into two pieces as it approached King Khalid International Airport in Riyadh. They believe the warhead continued toward the airport, while the rear section separated and was found among debris.

The New York Times reported the missile defense system may have hit the rear tube after it broke away from the warhead, or missed the missile entirely.

While debris was landing on the streets of Riyadh, videos on social media showed an explosion shaking the domestic terminal at the airport. Videos show smoke rising into the air, which suggested the point of impact was just beyond the runway, and emergency response vehicles were also seen at the end of the airport’s runway.

Analysts located the Patriot batteries that were fired at the missile and concluded its warhead flew over the top of the batteries.

Researchers on Lewis’s team worked to learn about the nature of the missile’s impact, and found the smoke plume from the blast was located just off the runway at the Riyadh airport. Satellite imagery showing ground damage from emergency response vehicles also suggested the missile’s warhead detonated near the runway.

“The Houthis got very close to creaming that airport,” Lewis told the New York Times.