The US said today it was considering its response to the hijack by Somali pirates of an American couple sailing the world with a yacht full of bibles.
Pirates say the captured yacht will make landfall in Somalia today, which would reduce the chances of a fast rescue dramatically.
The hijack mirrors the ordeal of British couple Paul and Rachel Chandler whose yacht was captured by pirates. They were held hostage in a stiflingly hot Somali region for 388 days and were released in November.
Pirates captured the Americans' yacht Quest on Friday, two days after a Somali pirate was sentenced to 33 years in prison by a New York court for the 2009 hijacking of the Maersk Alabama.
That case ended in a spectacular rescue when navy sharpshooters killed two pirates holding the ship's captain, Richard Phillips.
The Quest is the home of Jean and Scott Adam from California, who have been sailing around the world since December 2004, according to a website the Adams keep. Two other Americans were also believed to be on board.
The pirates are unlikely to hurt the four Americans because they will not win any ransom money, said Graeme Gibbon-Brooks, head of Dryad Maritime Intelligence. He said the pirates would be wise to abandon the yacht because the hijacking threatens their "business", which relies on ransoms from large shipping and insurance companies.
"They risk the collapse of their business model if they change their status quo and the American government deems that they pose an immediate threat to the safety of American citizens," he said.
"They've made a mistake and it's in the Somalis' business interest to get off the yacht as soon as possible."
The US military was monitoring the situation and Matt Goshko, a spokesman at the US embassy in Nairobi, Kenya, which oversees Somalia, said reports indicated there were four US citizens aboard the Quest.
"All relevant US agencies are monitoring the situation, working to develop further information, assess options and possible responses," Mr Goshko said.
Pirates have increased attacks off the coast of East Africa in recent years despite an international flotilla of warships dedicated to protecting vessels and stopping the pirate assaults. Multi-million ransoms are fuelling the trade and the prices for releasing a ship and hostages have risen sharply.
Pirates currently hold 30 ships and more than 660 hostages, not counting the attack against the Quest.
After the Maersk Alabama was hijacked in April 2009, US Navy sharpshooters fired on pirates holding Capt Phillips, killing two of them. The only pirate to survive was Abdiwali Abdiqadir Muse, who was sentenced to 33 years in prison this week.
A Somali pirate who gave his name as Bile Hussein said yesterday pirates from the Bari area of Somalia's northern region of Puntland captured the yacht.
He said the yacht was expected to arrive in Somalia today "if no problems happen on their way".
The Adams website chronicles the couple's travels over the last seven years, from El Salvador and Panama in 2005 to Fiji in 2007 and Singapore and Cambodia last year.
They most recently sailed from Thailand to Sri Lanka and India and were on their way to Oman when captured. Djibouti - the tiny East African country north of Somalia - had been next on their list. A satellite tracking system the couple uses showed them docked in Mumbai, India on February 1.
"Djibouti is a big refuelling stop. I have NO idea what will happen in these ports, but perhaps we'll do some local touring," the couple's website says.
The Adams, members of the Marina del Rey Yacht Club in California, run a Christian ministry, according to their website, and have been distributing bibles to schools and churches in remote villages in areas including the Fiji Islands, Alaska, New Zealand, Central America and French Polynesia.
The pirates from Puntland are not hardline Islamists and the fact the Adams carry bibles is not likely to be a problem. Pirates there are known to spend their ransom spoils on alcohol, drugs and prostitutes.
But the prison sentence given to Muse this week could have implications for the four US hostages. Pirates have turned increasingly violent in their attacks and naval officials say they have begun systematically torturing hostages and using them as human shields.
Earlier this week a pirate told an Associated Press reporter in Somalia that they would target Americans in retaliation for the sentencing.
The security minister in Puntland condemned the hijacking, called for an urgent rescue operation and for the pirates to be dealt with "relentlessly and mercilessly".
"We are not capable of stopping piracy. They have expertise and can reach far beyond Somali coastlines. Puntland will do its best to track them down," General Yusuf Ahmed Khary said.