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Dutch marines board a fishing boat and free two dozen Yemenis from Somali pirates. They seize and destroy AK-47s and a rocket-propelled grenade launcher but then put the nine bandits back in their skiff and set them free.

The Dutch government says its navy made a mistake, but Saturday's catch and release in the Gulf of Aden underscores confusion over what to do with captured pirates — and led to calls in Washington for tougher NATO action.

The Dutch marines were among a NATO flotilla that has helped fend off several pirate attacks in recent days in the crowded shipping lane off Somalia's coast; in each case the culprits were released amid questions over jurisdiction to arrest them.

That drew criticism from the Obama administration, which killed three Somali pirates and arrested one in the dramatic April 12 rescue of an American cargo ship's captain. The surviving pirate was arrested and sent to New York for trial.

Releasing pirates "sends the wrong signal," Secretary of State Hillary Clinton said after meeting her Dutch counterpart Maxime Verhagen in Washington on Monday. Both ministers said they would push for NATO to begin arresting pirates.

Both NATO and the European Union have multinational flotillas operating under a mandate from the U.N. Security Council which tasks them with escorting World Food Program ships and with patrolling the seas around the Horn of Africa. The mandate says nothing about how to treat captured pirates.

Angry Dutch lawmakers grilled the junior Defense Minister Jack de Vries on Tuesday about why a Dutch boarding party released the nine Somalis.

"We see piracy as a major problem but this weekend a Dutch ship detains pirates and then frees them," opposition lawmaker Ewout Irrgang said. "How can this happen? Do you agree that this is idiotic?"

De Vries admitted that Dutch prosecutors should have been consulted before the pirates were released.

"With hindsight, the commander contacted prosecutors too late," De Vries said. "It should have happened earlier."

Wim de Bruin, a spokesman for the Dutch national prosecution service, said the pirates could "in principle" have been put on trial under Dutch law even though no Dutch citizens or ships were targeted by the pirates.

"I suspect that in the next case the Defense Ministry will try to make contact with prosecutors," before freeing piracy suspects, De Bruin said.

Piracy is the oldest international crime in Dutch law books and can be prosecuted regardless of where it happens and who is targeted.

The Netherlands has showed its willingness to prosecute piracy by agreeing to try five Somalis arrested in January by the Danish navy. The trial is expected to start next month.

NATO says any decision to arrest and prosecute suspects is up to its individual member states, not the alliance.

"When a ship which is part of the NATO force detains a person, the detention is a matter for the national authorities," said Shona Lowe, a spokeswoman for the NATO naval command in Northwood, Britain.

NATO first started patrolling the sea lanes off Somalia in late October after the United Nations appealed for protection for its food aid ships.

Its flotilla was replaced in December by an EU task force with a one-year mandate. A new NATO squadron arrived in the area last month. It is scheduled to leave soon for Southeast Asia where it will make a number of port calls before returning to the Horn of Africa.

The European Union recently signed a Memorandum of Understanding with the government of Kenya, which allows its ships to land any captives in Kenya where they can be prosecuted under that country's legal system.

But NATO does not have the same agreement with Nairobi and — since it is a separate entity — any agreements between Kenya and the EU don't automatically apply to the NATO task force.

Officials say the problem is complicated by practical issues such as the massive size of the area being patrolled by a handful of warships: about 1.1 million sq. miles (3 million sq. kilometers), an area larger than the Mediterranean Sea.

Arresting pirates stretches the force even thinner as it can take several days to sail to and from Mombasa to drop off suspects, said a Western official involved with the anti-piracy effort.

The official, who asked not to be named because he was not authorized to speak to the media, pointed to the French frigate Nivose, which is part of the EU mission.

Commandos aboard the warship arrested 11 pirates last Wednesday, and the frigate sailed for Mombasa to hand them over to authorities there. It has still not returned to the Gulf of Aden, he said.

Even so, the London-based International Maritime Bureau, an organization that fights crime linked to ships and their cargoes, said arrests would help snuff out piracy.

"It would be a much greater deterrent if (captured pirates) are handed over to authorities for prosecution," said Cyrus Mody of the bureau. "Returning them isn't solving anything ... it is in fact sending the wrong signals."