The US military is carrying out an additional strike against the Houthis in Yemen, a day after launching a wave of attacks on nearly 30 locations in the country to degrade the Iran-backed rebel group’s ability to strike Red Sea shipping, two US officials tell Reuters.

The officials, who speak on condition of anonymity, declined to provide further details.

According to two US officials who speak anonymously to The Associated Press to discuss an operation that hadn’t yet been publicly announced, the strike targeted a Houthi-controlled site in Yemen that they have determined was putting commercial vessels in the Red Sea at risk.

The first day of strikes on Friday hit 28 locations and struck more than 60 targets. However, the US determined the additional location, a radar site, still presented a threat to maritime traffic, one official says.