The U.S. sent warships speeding to the scene. But they were hours away when the brazen pirates attacked, and the world’s greatest sea power had to face the fact that it had only limited options to respond to the startling seizure of American merchant seamen.

It’s a hard reality facing the Obama administration as it tries to thwart the growing threat of piracy at sea.

President Barack Obama was closely following the events, said Denis McDonough, a senior foreign policy adviser at the White House.

“We have watched with alarm the increasing threat of piracy,” McDonough said. “The administration has an intense interest in the security of navigation.”

The outcome for the U.S.-flagged Maersk Alabama and its crew was still unclear late Wednesday night off the coast of Somalia. The crew had retaken control of the cargo ship from a band of pirates, but the captain was still held by the attackers in one of the ship’s lifeboats.

Help was reported to be on the way.

U.S. officials said an American Navy destroyer, the USS Bainbridge, was headed for the scene along with at least six other vessels. The Bainbridge was among several U.S. ships, including the cruiser USS Gettysburg, that had been patrolling in the region but were several hours away when the Maersk Alabama was seized.

The Bainbridge is a guided missile destroyer carrying Tomahawk cruise missiles, torpedoes and two MH-60 Knighthawk helicopters armed with Hellfire missiles.

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

However it ended, the pirate-hostage drama, the first like this in modern history involving a U.S. crew, was part of a rapid increase in piracy off the vast Somali coastline. These attacks have netted the freebooters millions of dollars in ransoms, vexed the international shipping industry and left the U.S. and naval allies grasping at solutions.

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 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.

Three months into the international anti-piracy campaign, as many as 17 nations are participating in increased patrols, and more are expected to join.

But 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.

Navy officials have urged patience, saying the key will be to watch for progress over the next year to see if the increased patrols and agreements for piracy prosecutions begin to work.

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 issue of ordering strikes inside Somalia and said that, “ultimately, the solution to the problem of piracy is ashore — in Somalia.”