MOGADISHU, Somalia — As a heavily armed U.S. destroyer patrolled nearby and planes flew overhead today, a Somali pirate spokesman told The Associated Press his group was demanding a $20 million ransom to release a cargo ship loaded with Russian tanks.

The spokesman also warned that the pirates would fight to the death if any country tried military action to regain the ship, and a man who said he was the ship's captain reported that one crew member had died.

Pirates seized the Ukrainian-operated ship Faina off the coast of Somalia on Thursday as it headed to Kenya carrying 33 Russian-built T-72 tanks and a substantial amount of ammunition and spare parts. The ordnance was ordered by the Kenyan government.

The guided missile destroyer USS Howard was stationed off the Somali coast on Sunday, making sure that the pirates did not remove the tanks, ammunition and other heavy weapons from the ship, which was anchored off the coast.

A spokesman for the U.S. 5th fleet said the Navy remained "deeply concerned" over the fate of the ship's 21-member crew and cargo.

In a rare gesture of cooperation, the Americans appeared to be keeping an eye on the Faina until the Russian missile frigate Neustrashimy, or Intrepid, reaches the area. The Russian ship was still in the Atlantic on Sunday, the Russian navy reported.

Pirate spokesman Sugule Ali said he was speaking Sunday from the deck of the Faina via a satellite phone — and verified his location by handing the phone over to the ship's captain, who also spoke with the AP. It was not possible to further confirm their identities.

"We want ransom, nothing else. We need $20 million for the safe release of the ship and the crew," Ali said, adding that "if we are attacked, we will defend ourselves until the last one of us dies."

Five nations have been sharing information to try to secure the swift release of the ship and its crew — Ukraine, Somalia, Russia, the United States and Britain. Kenyan government spokesman Alfred Mutua, however, insisted his country will not negotiate with pirates or terrorists.

Ali said planes have been flying over the Faina. It was not known which country the planes belonged to. He also said others who made earlier ransom demands did not speak for the pirates holding the ship.

A man who said he was the captain of the seized ship and who identified himself as Viktor Nikolsky told the AP that a Russian crew member died Sunday because of hypertension.

"The rest of us are feeling well," Nikolsky said, adding that he could see three ships about a mile away, including one carrying an American flag.

Both Ali and Nikolsky spoke on a satellite phone number the AP got from a Somali journalist who spoke to Ali earlier in the day. The conversation lasted about 30 minutes. Ali spoke in Somali with a central Somalian accent and Nikolsky spoke in broken English.

Russian media had earlier identified Nikolsky as the first mate, yet he identified himself to the AP as the ship's captain. It was not possible to immediately resolve the discrepancy.

U.S. Navy spokesman Lt. Nathan Christensen told AP that the San Diego-based USS Howard had made contact with the Faina on Sunday.

"While we can't get into details, I will say there has been basic bridge-to-bridge communication established with the ship," Christensen told the AP in a phone interview from the 5th Fleet's Mideast headquarters in Manama, Bahrain.

Christensen said the Navy was aware of one crew member's death, but did know what the cause was.

Pirate attacks worldwide have surged this year and Africa remains the world's top piracy hotspot, with 24 reported attacks in Somalia and 18 in Nigeria this year, according to the International Maritime Bureau's piracy reporting center.

Attacking ships has become a regular source of income for pirates in Somalia, a war-torn country without a functioning government since 1991.

Christensen said the Faina was anchored off Somalia's coast near the central town of Hobyo.

"What's on board is of concern to us as much as the criminal activity," Christensen told the AP, adding that the Navy does not want the tanks and other weapons to end up "in the wrong hands."

Christensen refused to say what the crew of the American destroyer would do if the pirates began to offload the tanks and weapons.

"It's a very complex situation and we do not want to speculate on any particular aspect of it," he said.

According to its Web site, the USS Howard has surface-to-air missiles, Tomahawk cruise missiles, anti-submarine rockets, torpedoes, and a five-inch rapid-fire deck gun.

In the latest hijacking in the area, a Greek tanker with a crew of 19 carrying refined petroleum from Europe to the Middle East was ambushed Friday in the Gulf of Aden, according to the International Maritime Bureau.