"We know that they have fired at least one missile in retaliation" but it did not hit a vessel, Director of the Joint Staff Lieutenant General Douglas Sims told journalists.

"Their rhetoric has been pretty strong and pretty high. I would expect that they will attempt to some sort of retaliation," he said of the Huthis.

The assessment of damage from the strikes by the United States and Britain -- which targeted nearly 30 locations using more than 150 munitions -- is still ongoing, Sims said, noting however that the number of casualties is not expected to be high.

"Every target we struck last night was associated with a capability that has been employed in denying freedom of navigation in the Red Sea," he said.

The Huthis have carried out a growing number of drone and missile strikes on the key international shipping route through the Red Sea since the Gaza war erupted with Hamas's unprecedented October 7 attack on Israel.

The rebels -- who say they are acting in response to Israel's military assault on Gaza -- have controlled a major part of Yemen since civil war erupted there in 2014, and are part of the Iran-backed so-called "axis of resistance" arrayed against Israel.