US Navy SEAL Team Two (Echo Platoon) members take up guard positions as others fast rope  out of a SH-60 Seahawk, from Helicopter Antisubmarine Squadron One Five (HS 15,) to the flight deck during a practice boarding of USS Normandy (CG 60.)

WASHINGTON (AP) — The seizure of an American crew and cargo demonstrates the limits of U.S. military power in an international cops-and-robbers chase along a huge, lawless stretch of African coastline.

An American Navy destroyer, the USS Bainbridge, arrived off the Horn of Africa on Thursday near the Maersk Alabama, Kevin Speers, a spokesman for the ship company Maersk, told AP Radio. U.S. officials said earlier that the Bainbridge and at least six other vessels were headed to the area.

The Bainbridge was among several U.S. ships, including the cruiser USS Gettysburg, that had been patrolling in the region. But they were about 345 miles and several hours away when the Maersk Alabama was seized, officials said.

There is too much area to cover and too many commercial vessels to protect for full-time patrols or escorts. U.S. legal authority is limited, even in the case of American hostages and a cargo of donated American food. And the pirates, emboldened by fat ransoms, have little reason to fear being caught.

It was not clear what the military crews would do when they got there. Options could include negotiation, backed by the implicit threat of force.

Operations would probably include watching the ship through helicopters and unmanned aircraft overhead, as well as ships in the surrounding waters. In the past, surveillance aircraft, including unmanned drones, have flown over captured vessels to take photos and collect other information.

According to the Navy, it would take 61 ships to control the shipping route in the Gulf of Aden, which is just a fraction of the 1.1 million square miles where the pirates have operated. A U.S.-backed international anti-piracy coalition currently has 12 to 16 ships patrolling the region at any one time.

Along the Somali coastline, an area roughly as long as the Eastern Seaboard of the United States, pirate crews have successfully held commercial ships hostage for days or weeks until they are ransomed. In the past week, pressured by naval actions off Somalia, the pirates have shifted their operations farther out into the Indian Ocean, expanding the crisis.

Oceans of that immense size cannot be patrolled completely, even with high-tech detection equipment doing some of the work.

There are also legal questions about where and how to prosecute pirates and about how far the U.S. military can or should go to help or protect commercial ships.

In December, alarmed by increases in hijacking incidents, the Bush administration sought and won U.N. Security Council authorization to expand international naval operations against Somali pirates to allow the pursuit of suspects on the ground in Somalia.

The move, which came at a special session attended by then-Secretary of State Condoleezza Rice and other foreign ministers, was the fourth taken by the council in the second half of 2008 alone to combat the pirates.

U.S. defense officials say the only realistic solution is on shore in Somalia, where money from the piracy ransoms fuels militant activities in the largely lawless country.

Vice Adm. Bill Gortney, commander of the U.S. Navy’s 5th Fleet, told the House Armed Services Committee that the Pentagon is looking at the question of ordering strikes inside Somalia and said that, “ultimately, the solution to the problem of piracy is ashore — in Somalia.”

Associated Press writers Pauline Jelinek, Lolita C. Baldor, Pamela Hess and Matthew Lee in Washington and Jennifer Quinn in London contributed to this report.

Related info: “How do you tackle piracy?” – BBC article