Somali pirates attacked two ships off the Horn of Africa on Saturday, capturing a Belgian dredger and its 10 crew. NATO forces intervened in the other assault, chasing the pirates down and freeing 20 fisherman on a Yemeni dhow.

The high-seas attacks underscored the dangers in waters off Somalia and east Africa despite the best efforts of an international flotilla that includes warships from the United States and the European Union.

Pirates from anarchic, clan-ruled Somalia have attacked more than 80 boats this year and hold 16 ships and over 290 crew members hostage.

In the first attack, pirates hijacked the Belgian-flagged Pompei in the Indian Ocean, a few hundred miles (kilometers) north of the Seychelles islands, said Portuguese Lt. Cmdr. Alexandre Santos Fernandes, who is traveling with the NATO fleet patrolling the region.

Belgium reported that the ship sounded two alarms early Saturday indicating it was under attack on its way to the Seychelles. It had 10 crew: two Belgians, one Dutch, three Filipinos and four Croatians.

Hours later, pirates further north in the Gulf of Aden attacked a Marshall Islands-flagged tanker with small arms and rockets. Fernandes said that ship, the Handytankers Magic, issued a distress call shortly after dawn but escaped the pirates using "speed and maneuvers."

A Dutch frigate from the NATO force responded immediately to the distress call. It trailed the pirates "on a small white skiff, which tried to evade and proceed toward a Yemeni-flagged fishing dhow" that had been sized by the pirates a week ago, Fernandes said.

He said pirates were using the Yemeni vessel as a "mother ship," a boat that allows the pirates' tiny skiffs to operate far off the Somali coast.

The pirates boarded the dhow and Dutch marine commandos followed soon after, freeing 20 fishermen whose nationalities were not known. There was no exchange of fire and Dutch forces seized seven Kalashnikov rifles and one rocket-propelled grenade launcher.

Seven Somali pirates were detained, but they were soon released because "NATO does not have any detainment policy," Fernandes said. The seven could not be arrested or held because they were seized by Dutch nationals and neither the pirates, the victims nor the ship were Dutch, he explained.

The Gulf of Aden — a vital short cut between Europe and Asia — is one of the world's busiest shipping lanes. For that reason, it has been hard hit by pirates, who can earn $1 million or more in ransom for each hijacked vessel.

Pirates plucked from the sea by navy warships could be tried anywhere from Mombasa to New York, Paris to Rotterdam — but most are simply set free to wreak havoc again because of legal issues.

Among the difficulties facing prosecutors is assembling witnesses scattered across the globe and finding translators. Many countries are wary of hauling in pirates for trial for fear of being saddled with them after they serve their prison terms.

The United States, the European Union and Britain all have signed agreements with Somalia's southern neighbor, Kenya, clearing the way for a slew of court cases in the southern port city of Mombasa. And the most prominent recent case — a scrawny Somali teenage pirate who stormed the U.S.-flagged Maersk Alabama this month and was later arrested by the U.S. Navy — will be tried in New York.

French soldiers take pirates who have attacked French citizens to Paris; pirates who have attacked other nations are hauled to Kenya, such as the 11 seized Wednesday when the French navy found them stalking a Lebanese-owned ship. India took 24 suspects to Yemen, since half were from there. The Dutch took five suspects to Rotterdam, where they probably will be tried next month under a 17th-century law against "sea robbery."

Britain, the U.S., Germany and France have brought suspects to Kenya, which convicted 10 pirates arrested by U.S. sailors last year. Each is serving a sentence of seven years — the maximum. But a backlog of all sorts of cases in Kenya's courts could mean long delays in trying the pirates.

AccuWeather.com says weather in the region is likely to favor the pirates for the next several weeks. Very small waves and light winds make it easier for the pirates to operate the small speedboats they use to attack ships. Unrestricted visibility at day will help lookouts on vessels watching for attacks, but little or no moonlight works for the brigands, the weather service said.

A small town in Vermont, meanwhile, celebrated the return of the unassuming shipping captain lauded for helping his crew survive a piracy attack off Somalia.

Richard Phillips, captain of the Maersk Alabama, arrived Friday at his farmhouse in Underhill with his wife, Andrea, to find their home festooned with ribbons and "Welcome Home" balloons and the road full of flag-waving, cheering friends and neighbors.