MOGADISHU (AP) ― An American couple that has sailed the world with a yacht full of Bibles was hijacked by Somali pirates, and the U.S. said Saturday it is assessing possible options.

Pirates say the yacht will make landfall in Somalia on Sunday, which would reduce the chances of a fast rescue dramatically. A British sailing couple hijacked by pirates was held hostage in a stiflingly hot Somali region for more than a year.

Pirates hijacked the 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, a couple from California who has 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 won’t win any ransom money if they do, said Graeme Gibbon-Brooks, the head of Dryad Maritime Intelligence. He argued that the pirates would be wise to abandon the yacht because the hijacking threatens their business model, 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 U.S. military was monitoring the situation. Matt Goshko, a spokesman at the U.S. Embassy in Nairobi, Kenya, which oversees Somalia, said reports indicate there are four U.S. citizens aboard the Quest.

“All relevant U.S. agencies are monitoring the situation, working to develop further information, assess options and possible responses,” 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. Multimillion dollar ransoms are fueling 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, Navy sharpshooters fired on pirates holding Phillips, killing two of them. The only pirate to survive was Abdiwali Abdiqadir Muse, who was sentenced to 33 years in prison this week.

The best-known case of Westerners being held hostage in Somalia was that of Paul and Rachel Chandler, a British couple held for 388 days. The two, who were captured while sailing in their private yacht, were released in November.

A Somali pirate who gave his name as Bile Hussein said Saturday pirates from the Bari area of Somalia’s northern region of Puntland captured the yacht. Hussein said the yacht was expected to arrive in Somalia on Sunday “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 Feb. 1.

“Djibouti is a big refueling 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 ― who are members of the Marina del Rey Yacht Club in Marina del Rey, California ― run a Bible 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 Adams carry both Catholic and Protestant versions of the Bible, and at several different reading levels. The couple stamps the bibles with “A GIFT from your friends in the United States. Quest Bible Ministry. NOT FOR SALE,” after discovering a teacher who they gave Bibles to sold them.

The pirates from Puntland are not hardline Islamists and the fact the Adams carry Bibles is not likely to be a problem. Pirates in Puntland 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 American hostages. Pirates have turned increasingly violent in their attacks, and naval officials say pirates have begun systematically torturing hostages and using them as human shields.

Earlier this week a pirate told an Associated Press reporter in Somalia that pirates would target Americans in retaliation for the sentencing. The pirate, who identified himself by the name Hassan, said Americans would suffer “regrettable consequences.”

Pirates have recently tied hostages upside down and dragged them in the sea, locked them in freezers, beaten them and used plastic ties around their genitals, the commander of the European Union anti-piracy force, Maj. Gen. Buster Howes told AP this month.

The security minister in Puntland condemned the hijacking and called for an urgent rescue operations 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 bests to track them down,” Gen. Yusuf Ahmed Khary said.