The U.S. and U.K. carried out more airstrikes Monday on Houthi targets in Yemen, the eighth attack in 10 days.

It was the second time the U.S. and U.K. have coordinated on attacks on the Houthis.

The military coalition struck eight sites, according to CNN. Canada, the Netherlands, Bahrain and Australia supported the airstrikes.

Targets hit included an underground storage site and Houthi missile and surveillance capabilities, BBC reported. The U.S. and U.K. said they were “trying to protect the free flow of commerce.”

Why is the U.S. striking targets in Yemen?

The Yemen-based Houthis began attacking vessels in the Red Sea after the start of the Hamas-Israel war, following the Oct. 7 Hamas attack on Israel.

In early January, a United Nations Security Council resolution called for an “immediate” end to Houthi attacks in the Red Sea, per BBC. President Joe Biden ordered strikes on Houthi targets in Yemen for the first time following the resolution.

The attacks have affected major shipping routes and freight rates.

Who are Yemen’s Houthis?
What’s happening in the Red Sea?

Pentagon reacts to 8th strike

The Pentagon confirmed the Yemen attack in a Monday statement.

“Our aim remains to de-escalate tensions and restore stability in the Red Sea, but let us reiterate our warning to Houthi leadership: we will not hesitate to defend lives and the free flow of commerce in one of the world’s most critical waterways in the face of continued threats,” the statement read.

U.S. officials said that Iran has “been quietly fueling” the Houthis’ Red Sea attacks by supplying them with tactical intelligence and weapons, according to CNN.