The United States, Britain and a handful of other allies answered dozens of Houthi attacks on international shipping in the Red Sea and the Gulf of Aden with a series of powerful airstrikes designed to severely degrade the Iranian-backed group’s capabilities.

U.S. Central Command late Thursday said the series of strikes hit more than 60 targets at 16 locations in Houthi-controlled parts of Yemen, including command and control nodes, munitions depots, launching systems, and production facilities.

“We hit them pretty hard, pretty good,” a U.S. defense official, speaking on the condition of anonymity to discuss details of the operation, told VOA, adding the strikes also targeted Houthi radar installations and air defense systems which did not fire back.

A spokesperson for the Houthi rebel group said the strikes killed at least five fighters and wounded six others, without specifying the targets that were hit.

The U.S. and British strikes, carried out with the help of Australia, Canada, the Netherlands and Bahrain, were launched from fighter jets, surface vessels and submarines, the defense official said.

The U.S. alone, dropped more than 100 precision guided munitions on the Houthi installations, officials said, with the naval vessels and submarines firing Tomahawk Land Attack Missiles to take out the intended targets.

The official also said the targets were chosen both because of their threat to shipping and the lack of a civilian presence.

In a statement from the White House late Thursday, U.S. President Joe Biden called the strikes a “direct response to unprecedented Houthi attacks” on international shipping, saying they were necessary after attempts at diplomacy were ignored.

“These targeted strikes are a clear message that the United States and our partners will not tolerate attacks on our personnel or allow hostile actors to imperil freedom of navigation in one of the world’s most critical commercial routes,” Biden said. “I will not hesitate to direct further measures to protect our people and the free flow of international commerce as necessary.”

British Prime Minister Rishi Sunak likewise condemned the Houthi attacks as destabilizing, confirming the participation of British fighter jets in Thursday’s strikes.

“Their reckless actions are risking lives at sea and exacerbating the humanitarian crisis in Yemen,” Sunak said in a statement. “This cannot stand.”

It is the first time Houthi targets inside Yemen have been struck since the militants began attacking ships in the Red Sea following Hamas’ assault on Israel on October 7.

U.S. officials late Thursday were still studying the impact of the strikes against the Houthis, but an initial assessment suggested the damage to Houthi capabilities is “significant.”

“We were going after very specific capability in very specific locations with precision munitions,” said a senior U.S. military official, who briefed reporters on the condition of anonymity in order to discuss the operation.

“This was a significant action,” added a senior U.S. administration official. “[We have] every expectation that it will degrade in a significant way, the Houthis, a capability to launch exactly the sorts of attacks that they have conducted over the period of recent weeks.”

There have been 27 attacks launched from Houthi-held areas of Yemen since mid-November, impacting citizens, cargo and vessels from more than 50 countries, according to the U.S.

U.S. officials said in one instance last month, U.S. defensive action prevented a Houthi attack from hitting and likely sinking a commercial ship full of jet fuel.

The most recent Houthi attack, involving the launch of an anti-ship ballistic missile, took place earlier Thursday. The missile landed in the Gulf of Aden near a commercial vessel, causing no injuries or damage.

On Tuesday, U.S. Central Command, which oversees U.S. forces in the Middle East and South Asia, said the Houthis launched a complex attack using 18 one-way attack drones, two cruise missiles and one ballistic missile from Houthi-controlled areas of Yemen toward Red Sea shipping lanes where dozens of merchant vessels were transiting.

U.S. combat jets, along with U.S. and British military vessels, responded by shooting down the drones and missiles, averting any damage to ships or injuries to their crews in the area.

The senior U.S. administration official said it was Tuesday’s massive attack by the Houthis that prompted Biden to order Thursday strikes.

Before the U.S. and British-led strikes late Thursday, multiple U.S. officials warned both the Houthis and Iran against what they described as reckless and illegal behavior.

“There will be consequences,” Pentagon press secretary Major General Pat Ryder said Thursday in response to a question from VOA.

“The Houthis are funded, trained, equipped by Iran to a large degree. And, so, we know that Iran has a role to play in terms of helping to cease this reckless, dangerous and illegal activity,” he said.

Last week, the United States and 12 allies issued a statement warning the Houthis of unspecified consequences if their attacks on shipping in the Red Sea continued.

“Let our message now be clear: We call for the immediate end of these illegal attacks and release of unlawfully detained vessels and crews,” the statement said.

Signatories on the statement included Britain, Australia, Canada, Germany and Japan.

The statement followed the launch in mid-December of Operation Prosperity Guardian by the United States, Britain and nearly 20 other countries to protect ships from Houthi attacks.

Since the launch of Prosperity Guardian, at least 1,500 vessels have passed safely through the Bab el-Mandeb Strait, which connects the Red Sea with the Gulf of Aden.

The commander of U.S. Navy operations in the Middle East last week called it “the largest surface and air presence in the southern Red Sea in years.”

The U.N. Security Council issued its own resolution Wednesday, calling on the Houthis to stop the attacks immediately.

There are questions, however, as to whether the statements, backed now by the U.S. and British strikes against the Houthis, will do anything to deter Tehran.

“Iran has the luxury of really fighting a, what I would call, a hidden-hand operation with very few Iranians on the ground,” the former commander of U.S. Central Command, retired General Kenneth “Frank” McKenzie, told a webinar on Wednesday.

“They’re choking world shipping in the Bab el-Mandeb [Strait] at a very low, very low price for Iran,” he said.

But McKenzie argued that even if Iran continues to encourage the Houthis, the risk of a wider regional escalation is slim.

“I do not believe the escalation ladder leads out of Yemen. I believe it stays in Yemen,” he said. “And I believe Iran will leave their partners down there, their proxies down there, to their fate.”

U.S. officials said while they were bracing for the Houthis to try to mount some sort of response to the strikes, a slew of initial claims of attacks late Thursday appeared to be nothing more than disinformation.

This is not the first time the U.S. military has targeted Houthi launch sites in Yemen in response to militant attacks against vessels in nearby waters. In October 2016, the American destroyer USS Nitze launched Tomahawk cruise missiles at three radar sites along Yemen’s Red Sea coast in order to degrade the Houthi’s ability to track and target ships.