In their latest attack, Somali pirates have seized a 17,000-ton Danish cargo ship, the Maersk Alabama, in the Gulf of Aden. According to U.S. officials, the ship is U.S.-operated and is carrying some 21 Americans. It's the sixth vessel to be seized in just a week in the region. While an effort by foreign navies to more thoroughly police the waters around the region has reduced pirate attacks recently, the hijacking is a reminder that there are still frequent attempts by criminals to take over ships in the area. The pirates typically demand heavy ransoms in exchange for the vessels.