Cooper said have now been 25 attacks by the Houthis against merchant vessels transiting the southern Red Sea and Gulf of Aden He added “there are no signs that their irresponsible behavior is abating” WASHINGTON: A Houthi drone boat ladened with explosives detonated in the Red Sea on Thursday but failed to cause any damage or casualties, the US Navy said, as the Yemen-based group continued its attacks in defiance of international calls to stop. The latest attack came one day after 12 countries including the United States, Britain and Japan issued a joint statement cautioning the Houthis of unspecified “consequences” unless it halts its attacks, in what one US official on Wednesday suggested was a final warning. The Iran-aligned Houthis have launched wave after wave of exploding drones and missiles at commercial vessels since Nov. 19, trying to inflict a cost in what they says is a protest against Israel’s military operations in Gaza. The Houthi campaign has been extraordinarily disruptive to international shipping, causing some companies to suspend transits through the Red Sea and instead take the much longer, costlier journey around Africa. Vice Admiral Brad Cooper, who leads US Naval forces in the Middle East, told reporters on Thursday that the Houthi exploding boat drove out about 50 miles into the Red Sea and then detonated in dense shipping lanes. “It came within a couple of miles of ships operating in the area — merchant ships and US Navy ships — and we all watched as it exploded,” Cooper told reporters, adding the target of the attack was not clear. Cooper said have now been 25 attacks by the Houthis against merchant vessels transiting the southern Red Sea and Gulf of Aden and added “there are no signs that their irresponsible behavior is abating.” The United States and other countries last month launched Operation Prosperity Guardian to protect civilian vessels, which Cooper said now included contributions from 22 countries. So far, Cooper said US warships and US partners have shot down two cruise missiles, six anti-ship ballistic missiles and 11 drones. On Sunday, US warships sank three Houthi speed boats to protect a commercial vessel from being hijacked. A senior Biden administration official told reporters on Wednesday “if that happened again, we would probably do the exact same thing.” The same official, speaking on condition of anonymity, said the 12-nation statement to the Houthis was very clear. “I would not anticipate another warning,” the official said. At the United Nations, a US representative told the UN Security Council that the United States believed the situation in the Red Sea had reached an “inflection point.” Asked whether Operation Prosperity Guardian might target Houthi positions with strikes to prevent them from attacking ships, Cooper said that the 22-nation coalition was purely defensive in nature. “Anything that happens outside of the defensive aspect of this operation is a completely different operation,” he said. The Houthis have said their attacks on commercial shipping target vessels with Israeli links or were sailing to Israel. But many vessels have had no Israeli connection and were not bound for Israeli ports, and major shipping lines have suspended their operations through the Red Sea. Cooper said the ships that have been attacked have direct connections to 55 countries. “So regardless of the vessel’s company ownership or its destination, these Houthi attacks are for sure destabilizing and contrary to international law and clearly ... must stop immediately,” Cooper said.