'These warnings must be taken seriously, as pirates continue to put our ships and crews at risk, even one year after the Maersk Alabama incident,' said David T. Matsuda, acting maritime administrator. 'Mariners must be vigilant and prepare for potential attacks when in the region.'
Calmer seas enable pirates to operate further from shore and with larger mother ships, and cargo vessels are vulnerable up to 1,000 miles from shore, the advisory said.
MarAd and the Office of Naval Intelligence also recently warned U.S. vessel operators to be vigilant against the threat of al-Qaeda attacks off the coast of Yemen, suggesting the possibility of a suicide-boat attack like the one that severely damaged the USS Cole in 2000.
Other methods of attack could include missiles or projectiles, the advisory said.
Al-Qaeda in Yemen is an offshoot of the terrorist organization that has become more active in recent years and is considered behind the Christmas Day bombing attempt of a U.S. airliner in Detroit.
