Maersk Hangzhou issued a second distress call in less than 24 hours, reporting being under attack by four Iranian-backed Houthi small boats, U.S. Central Command said in its latest update.

"The small boats, originating from Houthi-controlled areas in Yemen, fired small arms weapons at the Maersk Hangzhou, getting to within 20 meters of the vessel, and attempted to board the vessel."

A contract embarked security team on Maersk Hangzhou returned fire, the update added.

"U.S. helicopters from the USS EISENHOWER (CVN 69) and GRAVELY (DDG 107) responded to the distress call and in the process of issuing verbal calls to the small boats, the small boats fired upon the U.S. helicopters with crew served weapons and small arms."

The U.S. Navy helicopters returned fire in self-defence, sinking three of the four small boats, and killing the crews. The fourth boat fled the area. There was no damage to U.S. personnel or equipment, the update added.

Maersk Hangzhou, a 15,200 TEU vessel, was hit by a missile while transiting the Southern Red Sea on December 30, and the Singapore-flagged, Denmark-owned/operated container ship requested assistance. "The USS GRAVELY (DDG 107) and USS LABOON (DDG 58) have responded to the ship. The vessel is reportedly seaworthy and there are no reported injuries," U.S. Central Command said in its latest update.

The USS GRAVELY shot down two anti-ship ballistic missiles fired from Houthi-controlled areas in Yemen toward the ships, the update added.

"This is the 23rd illegal attack by the Houthis on international shipping since November 19."

Maersk Hangzhou was last seen on AIS Friday afternoon entering the eastern end of the Gulf of Aden from the Indian Ocean and has not broadcast AIS data since, Lars Jensen said in his LinkedIn post.

"We are ending the year with the crisis being completely unresolved and presently with no clear solution in sight."

Questions are also being raised about Maersk's decision to continue Red Sea sailings even after repeated attacks.

"It looks like A.P. Moller - Maersk gamble did not pay off like they hoped as Maersk Hangzhou heading northbound to Suez was hit by a missile," Salvatore Mercogliano, Chair, Department of History Criminal Justice and Political Science, Campbell University said in his LinkedIn post.

Red Sea attacks double wages for Danish crew
The shipping industry in Denmark, home to some of the world’s largest firms, agreed to double wages for crew sailing through the Red Sea to compensate for the danger posed by the recent attacks, Bloomberg reported.

"The hazard pay kicks in for the time spent in two defined high-risk areas in the region, according to a deal presented on Friday by employer group Danish Shipping and the nation’s three largest labour unions for seafarers."