The U.S. and U.K. launched new airstrikes against eight Houthi targets in Yemen on Monday, the latest salvo in an allied effort to stop the group from harassing commercial shipping in the Red Sea.

Monday night’s allied strikes — the eighth round in 12 days — were meant to "disrupt and degrade” the Houthi capabilities and targeted an underground storage site and locations linked to the group's "missile and air surveillance capabilities,” according to a statement from the two countries and their allied partners.

The airstrikes were the most significant since the first wave of allied missile and Tomahawk launches earlier this month against the Houthis, which have caused chaos for shippers worldwide and disrupted traffic through a waterway that previously accounted for 12% of global trade. In the days since, the group, which receives financial backing from Iran, has vowed to step up its strikes.