Persistent attacks on ships in the Red Sea by Houthi rebels is “a crisis that the whole world needs to respond to,” U.S. national security adviser Jake Sullivan said Tuesday.

His message came on the same day the U.S. struck the Iranian-backed Houthis in Yemen for the third time in five days.

Speaking at the World Economic Forum in Davos, Switzerland, Sullivan said the drone and missile strikes on commercial ships go “way beyond being a regional challenge.”

“This is a global challenge,” he said. “We're talking about a vital artery of global commerce, a critical maritime choke point that's being held hostage. And countries and companies that have nothing to do with the Middle East whatsoever are being affected.”

On Friday, the U.S. and British militaries bombed more than a dozen sites used by the Houthis in Yemen, in a massive retaliatory strike using warship- and submarine-launched Tomahawk missiles and fighter jets, U.S. officials said.

A day later, the U.S. military struck another Houthi-controlled site in Yemen that it had determined was putting commercial vessels in the Red Sea at risk.

But the strikes have not stopped the Houthis’ assault. On Sunday, they launched an anti-ship cruise missile toward an American destroyer in the Red Sea. There were no injuries or damage reported. 

Then Monday, Houthi rebels fired a missile that struck a U.S.-owned ship just off the coast of Yemen in the Gulf of Aden. There were no injuries or significant injuries in that strike, the U.S. military said.

Sullivan said he was not surprised the attacks have continued. 

“We did not say when we launched our attacks, they're going to end once and for all, the Houthis will be fully deterred,” he said. “We anticipated the Houthis would continue to try to hold this critical artery at risk.”

Sullivan suggested the U.S. may “take further action” against the rebel group, adding, “But this need to be an all-hands-on-deck effort.”

Shortly after his speech, an American official said a new round of U.S. strikes hit anti-ship missiles in Yemen. 

The United Nations Security Council passed a resolution last week condemning the Houthi attacks that have disrupted global trade and demanding the group immediately cease launching strikes. 

Australia, Bahrain, Canada and the Netherlands also lended support to the U.S. and United Kingdom in last week’s strikes, which followed “followed extensive multinational coordination led by the United States,” Sullivan said.

Sullivan said the U.S. wants to avoid conflict from spreading in the Middle East, which is also faced with the ongoing war between Israel and Hamas. 

“Through a combination of steady deterrence and steadfast diplomacy, we seek to stop the spread of conflict and to create the conditions for deescalation,” he said. “Our approach is and remains focused on moving towards greater integration and stability in the region.”

The Associated Press contributed to this report.