Stepped-up attacks on commercial shipping in the Red Sea by Houthi rebels have disrupted international trade and led to increased efforts by the U.S. and its allies to patrol the vital commercial waterway and respond to threats.

A presumed Israeli strike hit a Beirut neighborhood this week, killing a senior Hamas official.

His death could provoke major retaliation by Lebanon’s powerful Hezbollah militia.

The military said Sunday that four small boats attacked a cargo ship and fired at responding U.S. helicopters, which returned fire and sank three of the boats.

Israel’s unprecedented air and ground offensive has killed more than 21,800 Palestinians and wounded more than 55,000 others, according to the Health Ministry in Hamas-ruled Gaza.