Pirates who seized an arms-laden Ukrainian vessel off the Somali coast lined up the 20 captive crewmen on the ship's deck to show a nearby American naval patrol that they were in good health, a U.S. Navy spokesman said Monday.

Pirates hijacked the MV Faina Sept. 25 as it was carrying a cargo of tanks, rifles and ammunition bound for Sudan. The hijacking, one of around two dozen reported attacks on ships off Somalia this year, raised concern that the sensitive cargo could fall into the hands of al-Qaida linked insurgents in Somalia.

On Sunday, U.S. sailors on nearby vessels were able to see the 20 crewmen — 17 Ukrainians, two Russians and a Latvian — as they stood along the rail of the deck.

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"They look healthy, they look like they're OK," said Lt. Nathan Christensen, deputy spokesman at the Middle East headquarters of the U.S. Navy's 5th Fleet in Bahrain. The ship's Russian captain died of a heart condition soon after the hijacking, officials in Moscow say.

A photograph taken by a U.S. sailor shows the men leaning forward against a deck railing as pirates armed with what appear to be rocket-propelled grenades and rifles keep watch a few steps away.

U.S. warships have been surrounding the vessel, and American sailors have maintained radio contact with the pirates and crew. The U.S. Navy is aiming to prevent the pirates from any attempt to offload the ship's military cargo.

The pirates have lowered an initial ransom demand from $20 million to $8 million and have withdrawn a threat to blow up the vessel if they don't receive the sum.