A militant group tied to Iran claimed on Wednesday that it had targeted two Saudi oil tankers with missiles and drones in the Red Sea. It would be the first such attack since the group announced a blockade aimed at Saudi Arabia.

The Saudi authorities had not confirmed the attacks by Wednesday evening, but the militant group, the Houthis, said in a statement that it had carried out the strikes because the tankers were violating its blockade. It claimed that the strikes had caused large fires to break out on both vessels.

The Houthis, a rebel group that controls a significant part of Yemen, announced the naval blockade on Monday. The move threatened to open a new front in the war rippling across the Middle East and to further disrupt global energy supplies already cut by fighting by the United States and Iran near the Strait of Hormuz.

Mohammed al-Basha, a U.S.-based risk adviser focused on Yemen, said the tanker strikes on Wednesday demonstrated that the Houthis were “racing up” the “escalation ladder.” He said the attacks could prompt a military response by Saudi Arabia, an Iranian adversary that has relied on Red Sea routes in recent months to export millions of barrels of oil.

The ships that the Houthis claimed they struck on Wednesday were the Layla and the Encelia, two Saudi-flagged oil tankers, according to public ship-tracking data. While the Layla was last tracked five days ago in the Red Sea, the Encelia was located there Thursday morning, the tracking data shows.

The Houthis also claimed that in addition to attacking the oil tankers, they forced around “10 ships to retreat and return.”

That claim also could not be independently verified, but at least six vessels did reverse course in the Red Sea on Monday and Tuesday after the militia warned shipping companies to avoid Saudi ports, according to Kpler, a maritime data firm. It was not clear if those ships were included in the Houthis’ count.

While the Saudis and the Houthis have been in a fragile stalemate since a cease-fire in 2022, tensions erupted last week when the Houthis accused Saudi Arabia of striking Yemen’s main international airport in Sanaa, the Yemeni capital, in a dispute over an Iranian plane that tried to land there. The Houthis retaliated by attacking the Abha airport in southern Saudi Arabia, the first direct Houthi strike on Saudi soil since early 2022.

The Houthis have weaponized their ability to disrupt shipping in the Red Sea before.

During the war in Gaza, which began in late 2023, the Houthis attacked commercial shipping in the Red Sea with drones, missiles and hijacking, trying to exert pressure on Israel and its allies. By some estimates, a Houthi blockade could affect more than 3 percent of the global oil market.

Ismaeel Naar contributed reporting.