Updated

The U.S. intelligence community didn't know that an American whom it had used as an informant was plotting the terrorist attack on Mumbai, according to an Obama administration review of the case.

While some facts about terror informant David Headley were available to U.S. officials before the Mumbai attacks, the U.S. did not make a connection between Headley and plots against India until after the attacks because of government policy and procedures that were in force at the time, the office of the Director of National Intelligence said in a statement Monday.

The intelligence office did not detail how those earlier standards may have limited agencies' awareness of Headley or what those standards were.

"Had the United States government sufficiently established he was engaged in plotting a terrorist attack in India, the information would have most assuredly been transferred promptly to the Indian government," according to the statement from the intelligence office.

The intelligence office did not respond to requests for further comment.

The Washington Post reported Saturday that the U.S. had received at least five warnings about Headley's possible links to terrorism. Headley worked as an informant for the Drug Enforcement Agency starting in the late 1990s, though the agency reportedly cut ties with him before the 2008 Mumbai attacks, the Post said. The assault killed 166 people.

Since October 2001, people close to Headley went to the FBI and U.S. embassy officials with concerns that he was working with terrorists and plotting an attack in India, according to the Washington Post.

Ben Rhodes, deputy national security director for strategic communications, said Monday that while the U.S. had information about Headley, it was not connected to planning the Mumbai attacks.

"What we have is various different kinds of information about David Headley that, again, weren't specific to a particular plot in India," said Rhodes, traveling with the president in New Delhi.

Headley pleaded guilty in U.S. federal court to laying the groundwork for the attacks. He told Indian interrogators in June that Pakistani intelligence officers were deeply intertwined with Lashkar-e-Taiba, the group blamed in the attack.

Headley was born in the United States but spent most of his childhood in Pakistan, moving back to America as a teenager to be with his mother after his parents divorced. He joined Lashkar-e-Taiba in 2001 after hearing a lecture by the group's leader, Hafeez Saeed, on the need for holy war.

Under a deal with prosecutors in the United States, Headley will not face execution if he continues to cooperate with their terrorism investigation. He could face up to life in prison and a $3 million fine when he's sentenced. As part of the plea bargain, the U.S. government agreed not to extradite him to India, Pakistan or Denmark for the charges for which he has admitted guilt.

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Associated Press writer Julie Pace in Washington contributed to this story.