American forces foiled two attacks off the coast of Yemen in the span of few hours on Thursday, drawing fresh focus to Houthi militants’ continued ability to cause turmoil in a vital trade waterway despite repeated US and UK military strikes.

US forces shot down a drone off Yemen’s southern coast in the Gulf of Aden at about 5 a.m. local time on Feb. 1, US Central Command said in a statement. About five hours later, they destroyed an unmanned vessel laden with explosives in the Red Sea. Two hours after that, two anti-ship ballistic missiles meant for a Bermuda-flagged cargo ship fell harmlessly in the Red Sea.

“US Central Command’s actions will protect freedom of navigation and make international waters safer and more secure for U.S. Navy vessels and merchant vessels,” according to the statement.

The continued attack highlighted how the Iran-backed Houthis still have the means and the will to harass ships in the Red Sea nearly three weeks after the US and its allies began targeting their launchers, radar stations and supply depots in a bid to end attacks that have disrupted shipping through the Red Sea.

The group has said the allies’ military strikes have only deepened their determination to target vessels in the region in the weeks since they began attacks to protest Israel’s military campaign against Hamas in the Gaza Strip.