WASHINGTON: The United States plans to undertake further strikes after the killing of three US troops by Iranian-backed fighters last weekend, White House National Security Adviser Jake Sullivan said on Sunday.

“We intend to take additional strikes, and additional action, to continue to send a clear message that the United States will respond when our forces are attacked, when our people are killed,” he told NBC’s “Meet the Press” program.

The United States and Britain launched strikes against 36 Houthi targets in Yemen on Saturday, in the second day of major US operations against Iran-linked groups following a deadly attack that killed three American troops in Jordan last weekend.

Hamas says US, UK strikes on Yemen to cause more ‘turmoil’

Saturday’s strikes targeted 13 sites in Yemen the Houthis have used to attack Red Sea shipping, the Pentagon said, one day after the US carried out a first wave of retaliatory strikes on more than 85 targets in Iraq and Syria linked to Iran’s Islamic Revolutionary Guard Corps.

They are the latest blows in a conflict that has spread into the Middle East since Oct. 7, when the Palestinian group Hamas stormed Israel from the Gaza Strip, igniting a war that has drawn Tehran-backed groups into attacks on US and Israeli targets on several fronts.

“What happened on Friday was the beginning, not the end, of our response, and there will be more steps - some seen, some perhaps unseen,” Sullivan told CBS’ “Face the Nation” program. “I would not describe it as some open-ended military campaign.”