A federal judge in Washington, D.C., on Thursday sentenced a Somali man to 25 years in prison for his admitted role as a pirate who helped hijack and hold a Danish merchant ship and its crew hostage for 71 days until a $1.7 million ransom was paid.

Jama Idle Ibrahim is already serving a 30-year prison term in the US after pleading guilty to being part of a group of six would-be pirates who mistakenly tried to hijack an American warship, the USS Ashland, in April 2010.

US District Judge Paul Friedman complied with a request of federal prosecutors to allow Mr. Ibrahim to serve the 25-year term concurrently with his existing 30-year term.

Under a plea agreement stemming from the USS Ashland case, Ibrahim agreed to plead guilty to participating in both the warship attack in April 2010 and the merchant ship hijacking in November 2008. In exchange, prosecutors suggested he would face no more than 30 years in prison.

His cooperation with prosecutors could be important in helping build cases against other accused pirates, including those captured with Ibrahim during the USS Ashland attack.

In the November 2008 hijacking of the Danish merchant ship M/V CEC Future, a group of Somali pirates in high-speed skiffs – and armed with AK-47 assault rifles, a rocket-propelled grenade launcher, and handguns – forced the crew to the bridge and directed the captain to navigate into waters off the Somali coast and drop anchor, according to court documents.

The crew was comprised of 11 Russian nationals, a Georgian national, and an Estonian national. The ship carried cargo for Houston-based McDermott International, with a replacement cost of $15 million.

Clipper Shipping, the Danish company that owns the ship, tried to negotiate the release of the crew, the ship, and the cargo. Negotiations continued for 71 days.

During the ordeal, the ship’s cook was forced to prepare meals not only for the 13 crew members, but also for 15 to 35 armed pirates who remained on the ship around the clock, court documents say.

Eventually, Clipper Shipping arranged for $1.7 million to be air-dropped to the hijacked ship. Two days later, CEC Future was allowed to resume its voyage.

Overall, Clipper Shipping estimates the hijacking cost the company $3.5 million.

There is no indication in court documents how much of the $1.7 million ransom went to Ibrahim. There is no apparent effort by the US government to recover any of it.

“Piracy is a grave offense against the laws of the United States and humanity,” the government’s sentencing memorandum says. “It is in the interests of the United States and all nations that acts of piracy be prosecuted to the fullest extent of the law.”

Prosecutors said in their memo that Ibrahim’s prison sentence might make others still in Somalia think twice before engaging in acts of piracy.

“A sentence of 25 years imprisonment in this case is likely to become known in the community of pirates…, and can have a real deterrent effect on others contemplating pirate activity,” the memo says.

In addition to the Danish merchant ship, Ibrahim was one of six Somalis in an open skiff that approached the USS Ashland in the predawn dark on April 10, 2010, roughly 100 miles off Yemen's coast in the Gulf of Aden. The men pulled alongside what they thought was an unarmed merchant vessel and began firing their AK-47s, according to court documents.

The Ashland responded with two rounds from its MK-38 Mod 2 heavy machine gun. The deck-mounted weapon is capable of directing 180 rounds a minute of 22 mm ammunition at a target.

The double shot left the skiff in flames and the pirates swimming for their lives. They were plucked from the sea and detained. Eventually, the six were sent to Norfolk, Va., to be tried for piracy.

After they were captured, court documents say, the Somalis claimed to be members of a group transporting people from Africa to Yemen. They said their larger vessel broke down near the Yemen coast and that they set out in the skiff to avoid detection by local authorities.

They said they fired their weapons into the air to attract the attention of the passing ship in the hope of gaining assistance.