The U.S. military says it flew thousands of spy flights over Colombian jungles trying to find and free three Pentagon contractors since their kidnapping in 2003.

In the end, it was a daring operation by Colombian military intelligence agents that finally rescued the American trio from leftist rebels.

Until this week's rescue, some U.S. government officials despaired that Tom Howes, Marc Gonsalves and Keith Stansell might ever be freed. Some counterterror, military and diplomatic officials familiar with Bush administration efforts to secure their release questioned whether enough was being done.

On Thursday, Col. William Costello, spokesman for the U.S. Southern Command, said the command made 3,600 intelligence, surveillance and reconnaissance flights, followed up on 175 intelligence leads and spent $250 million trying.

"We've been actively searching for these guys every day for the past five and half years," Costello said.

FBI spokesman Richard Kolko said the agency sent crisis negotiators and investigators on "countless trips to Bogota" since the kidnapping.

One official said a Defense Intelligence Agency cell that primarily works to track captured or missing U.S. troops has been working on the case of the civilian contractors, who had been held by the Revolutionary Armed Forces of Colombia since their drug-surveillance plane went down in the jungle in February 2003.

Another said it was U.S. intelligence that located the hostages.

A third said the U.S. Special Operations Command helped with surveillance that positively located the hostages within the past year using satellites, aircraft and ground reconnaissance — and had tracked them since then.

All three spoke on condition of anonymity because they were not authorized to speak on the record and the Bush administration was adamant about giving the Colombians the credit.

"This was a Colombian-planned and Colombian-executed operation," State Department spokesman Sean McCormack told reporters. "We were in a supporting role."

Officials have said the U.S. and Colombian governments have known the location of the hostages a number of times over the years — and planned rescue missions several times. But they didn't attempt them because of the difficulty of the jungle terrain and the risk that the hostages could be killed.

Finally, it was a trick by Colombian spies that persuaded the rebels to hand over the men, along with kidnapped presidential candidate Ingrid Betancourt and 11 others on Wednesday.

Colombian Defense Minister Juan Manuel Santos said military intelligence agents infiltrated the guerrilla ranks and led the local commander in charge of the hostages to believe they were being taken to the guerrillas' supreme leader.

The reluctance of U.S. officials to highlight the U.S. role may be a reflection of American politics.

Congressional support for Plan Colombia — the multibillion-dollar U.S. aid package to Colombia to help it fight its war on drugs and the insurgency — has rested heavily on promises that no U.S. troops would be put at risk and drawn into a jungle war with rebels, said George Withers, senior fellow with the Washington Office on Latin America, a human rights advocacy organization.

Congress has capped the number of American troops and contractors to explicitly limit the extent of U.S. involvement there to under 1,500 people, which indicates Congress' wariness of U.S. military involvement in action there, Withers said.

Several officials charged last year that there was a White House reluctance to forcefully pursue a rescue — or to press the Colombian government to step up its own efforts. That infuriated some career government negotiators, frustrated the men's employer, a Northrop Grumman subsidiary, and baffled the contractors' relatives, who could not understand why the men languished so long.

At one point, the Justice Department warned Northrop Grumman against sending backpacks of sneakers, medication and other items to the hostages, according to several people familiar with the conversations. The government cautioned that if the items ended up in the hands of rebels, it would violate the USA Patriot Act's ban on providing material support to terrorists, the people said.

Several current and former U.S. officials said the Bush administration failed to engage in routine negotiations or take other diplomatic steps of the kind used in similar hostage situations. That included deploying Foreign Emergency Support Teams, which are Washington-based special squads made up of counterterror experts and crisis workers from the departments of State, Justice, Defense, and the 16-agency intelligence community.

The State Department said the teams were not deployed because there wasn't enough information about the hostages' location or whether they were alive.

Some officials also charged that intelligence gathering on the hostages was limited by the administration's focus on disrupting terrorists in Iraq and elsewhere in the Middle East.

In a Jan. 23, 2007, letter to Northrop Grumman Vice President James F. Pitts, President Bush's national security adviser, Stephen Hadley, said the administration had "increased resources devoted to this issue in Bogota," including "fully leveraging all intelligence and available national resources." A copy of the letter was obtained by the Associated Press.