Israeli forces unleashed a series of strikes on the Yemeni capital, Sanaa, and the western city of Hodeidah on Thursday, killing at least six people and injuring dozens more, the Iran-backed Houthis said in a statement where it vowed to retaliate.

The latest round of strikes occurred as the United States and its ally Israel struggle to halt a campaign of regional assaults by Yemen’s Houthi militants.

The Houthis, who are backed by Iran, have targeted commercial ships in the Red Sea in solidarity with Hamas in Gaza. They launched a missile at Israel overnight.