NAIROBI, KENYA - Tensions increased Sunday over what to do about the arms-laden ship hijacked off the coast of Somalia, as the pirates vowed to fight to the death, a hostage died and Somali officials urged the U.S. Navy to send in commandos.

The pirates said that they could see a U.S. destroyer and military aircraft tracking them but that they were not afraid, according to a BBC report.

Said a man who said he was a spokesman for the pirates: "We will fight, and everyone here will die with us."

The man said he was speaking on a satellite phone from the bridge of the hijacked ship, and to prove it he handed the phone to another man who said he was the captain. The captain, a Ukrainian, then told the BBC that a Russian crew member had died from hypertension.

The Ukrainian ship was hijacked as it headed to Kenya with a large supply of arms, including 33 battle tanks, grenade launchers and ammunition.

The pirates said they would not release the 20 crew members or the arms until they were paid $20 million in cash.

Somali officials, warning of the danger if Islamic insurgents get the arms, said the only solution may be storming the ship. U.S. military officials said there were no plans to raid it.