U.S. officials have found no direct ties between East African pirates and terrorist groups but continue to search for signs of links in the wake of the Indian Ocean hostage incident.

It was not clear whether officials were specifically scrutinizing the Somali pirates who boarded the Maersk Alabama on Tuesday and fled in a lifeboat after taking the cargo ship's captain hostage.

Military and counterterrorism officials say that in the transient world of Somalia's combative coastal dwellers, a Somali clansman can be a fisherman one day, a pirate the next, and a weapons trafficker the following day.

"If you look at the clan structure or the tribes — to think that there may not be linkages probably is a bit naive," Army Gen. William "Kip" Ward, head of the Pentagon's Africa Command, told The Associated Press in an interview Thursday.

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Pirate Hijacking Resolutions at a Glance.

Michael Leiter, director of the National Counterterrorism Center, warned that some of the money from piracy could make its way into the hands of extremists.

"I certainly would not put that out of the realm of possibility," Leiter said at the Aspen Institute.

When hijackings first spiked off the coast of Somalia last year, counterterrorism officials pressed for any evidence that the country's extremist factions, or even Al Qaeda militants operating in East Africa, might be using piracy to fund their violence.

But the complicated clan structure and Somalia's ungoverned black market have made it difficult to trace the cash transactions.

In one indication that the groups sometimes have conflicting agendas, members of the al-Shabab terrorist organization lashed out publicly at a group of pirates late last year after they attacked the Sirius Star, a Saudi oil tanker.

A senior U.S. military official familiar with the region, speaking on condition of anonymity in order to discuss intelligence gathering, said the military is still looking hard at potential connections between piracy and the escalating terrorist activities in east Africa.

A key concern for the military, the official said, is the steady flow of black-market weapons, including rocket-propelled grenades, from Yemen into Somalia, where militants use them in both on- and offshore crimes.

According to a memo prepared by the staff of the U.S. House of Representatives Armed Services Committee in early March, five well-organized pirate groups conduct most of the pirate attacks off the coast of Somalia, but they hire local fisherman to ferry them out to their quarry to avoid detection.

It is very much a business. According to the memo, one captured pirate explained how the ransom — on average $1 million to $2 million per boat — is divided among participants. Twenty percent goes to the bosses of the group, 20 percent is capital investment, to include guns, ammunition, fuel, food, cigarettes and other provisions for future missions, 30 percent to the pirates, and 30 percent in bribes to government officials.

In 2008, pirates operating off Somalia earned $30 million in ransom through the seizure of 42 vessels.

The pirate groups draw their members from large provincial clans, which are extended family networks that divided themselves into smaller subclans, the memo reported.