Enlarge AFP/Getty Images Somali pirates stand in the dock during their trial in Sanaa on May 18, 2010. A Yemeni court sentenced six Somali pirates to death and jailed six others for 10 years each for hijacking a Yemeni oil tanker and killing two cabin crew in April last year. Pirates have stepped up their attacks off the coast of Somalia this year despite a large international naval flotilla designed to protect merchant shipping in the Horn of Africa region. "The pirates are becoming more brazen," said Lt. Cmdr. Corey Barker, a spokesman for the U.S. 5th Fleet, headquartered in Bahrain. Pirates launched 47 attacks in the region off the east coast of Somalia in the first four months of this year, up from 37 during the same period last year, according to U.S. 5th Fleet statistics. Not all of the attempts were successful, but the increase reflects a shift in tactics by pirates. The heavy presence of international forces has forced pirates farther afield. "They're going to greater lengths now," Barker said of the pirates. U.S. officials have said the piracy problem can be solved only by establishing order in Somalia, a lawless country where pirates thrive. "As we work to combat piracy's impact at sea, we are also working to address the conditions in Somalia that (have) allowed piracy to take root," said Robert Maggi, the State Department's counter-piracy coordinator. Somalia, however, remains chaotic and even a large naval flotilla has struggled to provide security over the 1.1 million square miles of ocean they patrol. "The answer is not sending billions of dollars of warships to chase a ship worth $1,000," said James Kraska, a professor at the U.S. Naval War College. "You're not going to win that game." After a rash of pirate attacks in 2008, the international community rushed a flotilla of naval ships into the waters off the Horn of Africa in an effort to protect international shipping passing through the Gulf of Aden. Today, there are an average of about 25 ships patrolling the area. The naval forces have established a 464-mile-long corridor for about 33,000 vessels that use the Gulf of Aden each year. "Within this corridor, the pirates' success rate has fallen to nearly zero," Maggi said. But pirates have moved outside the area to prey on ships, adjusting their tactics to reach farther from the coast. Pirates sometimes use so-called mother ships to launch smaller skiffs once they are in range of their target. "It's just pushed the problem elsewhere," said Peter Chalk, an analyst at RAND Corp., a think tank. Overall, the number of attacks in the Horn of Africa waters has increased, but the ratio of attacks that have been successful has dropped. "We've prevented more," Barker said. Officials attribute the increased success in averting attacks to the naval presence and evasive maneuvers and other tactics used by merchant ships. Merchant ships are using concertina wire and electrical fencing to keep pirates from boarding ships. Some ships carry armed security guards. Using those types of evasive tactics and techniques is a proven deterrent against hijacking, Lt. Matt Alden said. Pirates generally hijack ships and hold the vessels and crews for millions of dollars in ransom. Prosecuting pirates, who work in international waters, has remained a problem. "These guys aren't going to stop anytime soon," Chalk said. "The risk of being caught is low, prosecution is lower." Contributing: Paul Overberg Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more