The U.S. federal piracy trial of five Somali nationals has begun in the eastern U.S. city of Norfolk, Virginia.
The suspects are accused of firing at the USS Nicholas, a guided missile frigate, off the coast of Seychelles, on March 31.
Prosecutors say the Somalis mistook the naval ship for a merchant vessel.
The piracy trial is the first in the United States in more than a century.
The trial is expected to last about a month.
A Kenyan court this week released nine Somalis accused of piracy, saying it has no jurisdiction to try their case.
The International Maritime Organization says Somali pirates are currently holding 20 ships and at least 438 sailors and passengers.
The United Nations says Somalia's piracy problem is outpacing international efforts to fight it.
The U.N. undersecretary for political affairs, Lynn Pascoe, told the Security Council Tuesday that pirates are taking greater risks and seeking higher ransoms.