Yemen’s Iranian-backed Houthi rebels launched a missile Friday at a U.S. warship patrolling the Gulf of Aden, forcing it to shoot down the projectile, and also struck a British vessel as their aggressive attacks on maritime traffic continue.

The attack on the destroyer USS Carney marked a further escalation in the biggest confrontation at sea the U.S. Navy has seen in the Middle East in decades.

The anti-ship ballistic missile was fired at about 1:30 p.m. local time Friday from Houthi-controlled Yemen toward the USS Carney, U.S. Central Command reported. The missile was shot down by the Carney and caused no damage or injuries.

A little over six hours later, on Friday evening, the British military’s United Kingdom Maritime Operations, which oversees Mideast waterways, acknowledged a vessel had been struck by a missile and was on fire in the Gulf of Aden.

The anti-ship ballistic missile struck the M/V Marlin Luanda — which is British-owned but flies under a Marshall Islands flag — at about 7:45 p.m. local time, CENTCOM reported.

The ship was damaged, but no injuries were reported, CENTCOM said, adding that the USS Carney “and other coalition ships have responded and are rendering assistance.”

The attack on the Carney represents the first time the Houthis directly targeted a U.S. warship since the rebels began their assaults on shipping in October, a U.S. official said on condition of anonymity because no authorization had been given to discuss the incident.

Houthi military spokesman Brig. Gen. Yahya Saree did not acknowledge the Carney attack, but claimed the missile attack on the commercial vessel that set it ablaze, identifying the vessel as the Marlin Luanda.

The Houthi’s now-direct attacks on U.S. warships are the most aggressive escalation of its campaign in the Red Sea since the Israel-Hamas war broke out. The U.S. has tried to temper its descriptions of the Houthi’s strikes and said it is difficult to determine what exactly the Houthis are trying to hit, in part try to prevent the conflict from becoming a wider regional war.

The U.S. military has been conducting airstrikes against the Houthis to degrade their capabilities since Jan. 11, after several weeks of attacks on commercial ships by the militant group. 

The U.S. has launched multiple rounds of two different types of airstrikes — those hitting a wider range of targets, like storage sites and radar capabilities, and also preemptive strikes aiming at Houthi missiles as they’re loaded onto launchers to prepare for an attack. This second category — colloquially referred to as “whack-a-mole” strikes — have become an almost daily occurrence. 

But those U.S. attacks have not seemed to deter the Houthis. On Wednesday, Houthis launched anti-ship ballistic missiles at the U.S.-owned, flagged and operated commercial ship Maersk Detroit. The U.S. Navy destroyer USS Gravely shot down two missiles and a third fell into the water. There were no indications of damage or injuries in the attack.

Acknowledging Friday’s assault as a direct attack on a U.S. warship is important, said Brad Bowman, a senior director at the Foundation for the Defense of Democracies.

“They’re now finally calling a spade a spade, and saying that, yeah, they’re trying to attack our forces, they’re trying to kill us,” he said.

Tempering the language and response, while aimed at preventing a wider war, has had the opposite effect of further emboldening the Houthis, Bowman said.

The attacks were the latest assaults by the rebels in their campaign against ships traveling through the Red Sea and surrounding waters, which has disrupted global trade amid Israel’s war on Hamas in the Gaza Strip.

Since November, Houthi rebels have repeatedly targeted ships in the Red Sea, saying they were avenging Israel’s offensive in Gaza against Hamas. But they have frequently targeted vessels with tenuous or no clear links to Israel, imperiling shipping in a key route for global trade between Asia, the Mideast and Europe.

Since the airstrike campaign began, the rebels now say they’ll target American and British ships as well.

The U.S. Navy’s top Mideast commander told the Associated Press Monday that the Houthi attacks were the worst since the so-called Tanker War of the 1980s. It culminated in a one-day naval battle between Washington and Tehran, and also saw the U.S. Navy accidentally shoot down an Iranian passenger jet, killing 290 people in 1988.