Earlier this month Somali pirates release German ship held since May . The U.S. Navy says the pirate attack was a "deliberate attack" and that it is investigating whether any Americans were on board. Gulf of Aden , off northern Somalia , has the highest risk of piracy in the world .
Earlier this month Somali pirates release German ship held since May . Its crew was unharmed , NATO says . Gulf of Aden , off northern Somalia , has the highest risk of piracy in the world .