US retaliatory airstrikes updates: White House vows to take 'more action'

The U.S. will take "more action" against Iran-backed militants in response to the deadly drone attack in Jordan last week, the White House's national security adviser said in an interview on Sunday.

"This was the beginning of our response, there will be more steps," Jake Sullivan told ABC News "This Week" anchor George Stephanopoulos. "Some of those steps will be seen, some may not be seen. But there will be more action taken to respond to the the tragic death of the three brave U.S. service members."

The U.S. has blamed Iran-backed fighters for the attack on Tower 22 in Jordan on Jan. 28.

Iran has denied involvement. Pressed by Stephanopoulos whether additional strikes could escalation tension with Iran, Sullivan said it's something the U.S. is prepared for.

"This is something that we have to look at as a threat," he said. "We have to prepare for every contingency, and we are prepared for that contingency. And I would just say, from the perspective of Tehran, if they chose to respond directly to the United States, they would be met with a swift and forceful response from us."

-ABC News' Fritz Farrow

Early Sunday morning, the United States conducted a strike "in self-defense against a Houthi anti-ship cruise missile prepared to launch against ships in the Red Sea," a statement from the U.S. Central Command forces said.

Around 4 a.m. locally, U.S. forces identified a cruise missile in Houthi-controlled areas of Yemen and determined it presented an imminent threat to U.S. Navy ships and merchant vessels in the region, according to CENTCOM.

According to the release, "This action will protect freedom of navigation and make international waters safer and more secure for U.S. Navy vessels and merchant vessels."

The round of airstrikes launched by the U.S. and U.K. on Saturday “further degraded the Houthis’ capability to continue their illegal and reckless attacks" against U.S. ships and international commercial vessels, according to a senior U.S. administration official.

"The U.S. does not want escalation, and these strikes are directly in response to the actions by the Iranian-backed Houthis," the senior administration official said. "They are unrelated to the action the United States took on Friday in response to the continued attacks on our troops and facilities in Iraq and Syria."

The official emphasizes that the U.S. has “rallied a global coalition” to condemn and hold the Houthis accountable, adding that this is the third round of strikes as part of the coalition that includes the U.S., UK, Australia, Bahrain, Canada, the Netherlands, and now also Denmark and New Zealand.

-ABC News' Selina Wang

The U.S. and U.K. led a coalition of strikes against Houthis in Yemen focused on degrading the Houthis capabilities in shipping attacks, US officials say, stressing that the strikes are unrelated to strikes against targets in Iraq and Syria on Friday which were in response to the attack on U.S. troops in Jordan. Earlier reporting said the attacks on Yemen were in response to the attack on U.S. troops in Jordan.

While the timing may be coincidental, both the militia groups in Iraq and Syria, and the Houthis are backed by Iran, U.S. officials say. But when asked if there was an intended message for Iran as well, the U.S. officials said they did not want to focus on Iran and instead kept the discussion about how each of the airstrikes was intended to deter and degrade Iran’s local proxies.