President Barack Obama yielded to political opposition Monday, agreeing to try the self-professed mastermind of the September 11 attacks in a military tribunal at Guantanamo and not in a civilian court as he had promised.

Attorney General Eric Holder blamed lawmakers for the policy reversal, saying their December decision to block funding for prosecuting the 9/11 suspects in a New York court "tied our hands" and forced the administration to resume military trials.

His announcement was an embarrassing reversal of the administration's decision in November 2009 to try September 11 mastermind Khalid Sheikh Mohammed and four co-conspirators in a court near the site of the World Trade Center attack that killed nearly 3,000 people.

That decision had been welcomed by civil rights groups but strongly opposed by many lawmakers -- especially Republicans -- and New Yorkers, who cheered Holder's announcement that the Obama administration had reversed course.

In moving the case back to the military system, the Justice Department unsealed a nine-count criminal indictment that detailed how Mohammed trained the 9/11 hijackers to use short-bladed knives by killing sheep and camels.

Another of the five -- Walid bin Attash -- tested air security by carrying a pocket knife and wandering close to the doors of aircraft cockpits to check for reactions, said the indictment, which prosecutors asked the court to drop so the case can be handled by a military commission.

Prison Still Holds 172 People

The decision to abandon civilian prosecution was an admission that Obama has not been able to overcome political opposition to his effort to close the prison for terrorism suspects and enemy combatants at Guantanamo Bay in Cuba, a key 2008 campaign promise. It came on the day he kicked off his campaign for re-election in 2012.

James Carafano, a foreign policy expert at the conservative Heritage Foundation think tank, said a military trial for the five men was "the only rational course of action" and Obama was unlikely to be hurt politically by the decision.

"The (U.S.) public basically just ignores the issue these days. Even overseas, Europeans who were so critical before of Guantanamo have really gone to sleep on the issue," he said.

Obama has called the Guantanamo Bay facility, set up by his predecessor President George W. Bush, a recruiting symbol for anti-American groups and said allegations of prisoner mistreatment there had tarnished America's reputation.

He promised to close the prison by the end of his first year in office, but that deadline passed with no action as the administration confronted the hard reality of finding countries willing to accept custody of the inmates.

The prison still holds 172 people, down from 245 when Obama took office in January 2009.

Decision Welcomed

The decision to try the five men before military commissions was praised in New York and Washington. New York City Mayor Michael Bloomberg said the cost of holding and securing the trials in Manhattan would have been near "a billion dollars" at a time of tight budgets.

Chuck Schumer, a Democratic senator for New York, called it "the final nail in the coffin of that wrong-headed idea."

Julie Menin, who spearheaded opposition to the trials in New York, said the decision was a "victory for lower Manhattan and my community."

But others, like Valerie Lucznikowska, said the use of military commissions was "just not satisfying to people who want real justice." The 72-year-old New Yorker, whose nephew died in the World Trade Center attack, said the military commissions could be viewed by the world as "kangaroo courts."

Holder said he still believed the 9/11 suspects would best be prosecuted in U.S. civilian courts, despite strong congressional opposition.

Captain John Murphy, the chief prosecutor of the office of military commissions, said his office would swear charges in the near future against the five suspects for their alleged roles in the 2001 attacks.

In addition to Mohammed, an al Qaeda leader captured in Pakistan in 2003, and bin Attash, the accused co-conspirators are Ramzi Binalshibh, Ali Abdul Aziz Ali and Mustafa Ahmed al Hawsawi.