NATO joined a growing international force to protect vessels off Somalia`s perilous coast Thursday, sending military ships to the treacherous waters where pirates are negotiating the release of an arms-laden tanker, AP reported.

The pirates softened their ransom demands for the Ukrainian ship hijacked two weeks ago in a brazen high-seas attack. Pirates have seized more than two dozen ships off Somalia`s coast this year but the MV Faina has drawn the most international concern because of its dangerous cargo — 33 tanks and other heavy weapons.

"We are open for give-and-take negotiations," pirate spokesman Sugule Ali told The Associated Press via satellite telephone, as a helicopter could be heard buzzing overhead. Six U.S. warships have surrounded the boat, and a Russian frigate is expected within days.

Ali had vowed in earlier interviews never to reduce the ransom fromUS$20 million (euro14.57 million).

Despite his willingness to negotiate, Ali vowed to "cause a lot of problems for the world" if foreign powers use force to end the two-week standoff. If the ransom is paid, he said, the ship will be released.

NATO defense ministers meeting in Hungary agreed that a seven-ship force would be in the region within weeks.

"There will soon be NATO military vessels off the coast of Somalia, hopefully deterring piracy and escorting food shipments," NATO Secretary-General Jaap de Hoop Scheffer said. "That`s good news for the people of Somalia and, as it should be, bad news for the pirates."

De Hoop Scheffer said "millions of Somalians risk starvation if" aid is prevented from reaching the country.

NATO said a NATO naval group based in the Mediterranean Sea would sail to the Horn of Africa and stay until at least December.

Momentum has been growing for coordinated international action against the pirate menace after the seizure of the MV Faina. Several European Union countries last week said they would launch an anti-piracy patrol, and Russia announced it would cooperate with the West on fighting the pirates.

The U.N. Security Council this week called on countries to send naval ships and military aircraft, and U.S. warships are being diverted from counterterrorism duties to respond to the sea bandits.

Somalia`s government has given foreign powers the freedom to use force against the pirates.

The U.S. Navy said the 20 crew members aboard the MV Faina were living in fear.

"They want it to end peaceful and quickly," said Lt. Nathan Christensen, a spokesman from the U.S. 5th Fleet in Bahrain. He said the Navy was in regular radio contact with the crew.

But pirate spokesman Ali said the crew was holding up well.

"Their chef still prepares their food for them," he said. "They are healthy and have no worries. But of course their only worry is when they will gain their freedom. Their feeling is typically that of hostages — no more, no less."

Ukraine`s Foreign Ministry said that authorities in Somalia had been unhelpful.

"Over the past 20 years, criminal groups on the territory of Somalia have taken deep roots, possess big financial resources and are heavily armed and well organized," it said. "The pirates` only aim is to get a ransom and safely move deep onto the territory of Somalia."

Other Somali pirates released 15 Filipino seamen and four other crewmen seized when a Japanese-operated chemical tanker was hijacked nearly two months ago, officials said Thursday. Pirates still hold 67 Filipino sailors on four different ships.

Somalia, a nation of around 8 million people, has not had a functioning government since 1991. A quarter of Somali children die before age 5 and nearly every public institution has collapsed.

Islamic militants with alleged ties to al-Qaida have been battling the government and its Ethiopian allies since the Islamists were driven from the capital in December 2006.