President Barack Obama on Monday shared with India results of a probe into why US intelligence did not act on warnings about an American man who emerged as a key figure in the 2008 Mumbai attacks.
Senior officials said Obama brought up the case of David Coleman Headley in talks with Prime Minister Manmohan Singh, adding that some details of the probe by the Director for National Intelligence (DNI) would be released publicly soon.
According to a report in The Washington Post, the probe shows US officials had information building up on Headley's links with Islamic militants, over seven years, but did not question him or put him on any watch list.
"The president shared some of the results of that review with Prime Minister Singh," Ben Rhodes, a deputy national security advisor, told reporters after the two leaders met in New Delhi.
"What I think we found is the United States had pieces of information that came in about David Headley.
"They were not the kinds of information we were able to connect, for instance, to the plotting in Mumbai," he said.
Rhodes said the US government had provided general information about the attacks to India before the Mumbai strikes, but that the data was not specific.
Headley, the son of a former Pakistani diplomat and a white American woman, is being held in the United States.
He has confessed to helping plan the Mumbai attacks and in exchange for pleading guilty US prosecutors agreed he would not face extradition to India or the death penalty.
Specifically, he admitted to scouting the hotels and other sites that were targetted in the eventual assault by 10 Islamist militants, which killed 166 people.
The Mumbai attacks have been a theme of Obama's current trip to India.
He stayed in the Taj Mahal Palace hotel in Mumbai, which became the focus of the assault, and met survivors and victims' relatives.
The Post and ProPublica, an investigative journalism group, revealed that one of Headley's wives had warned FBI agents in August 2005 that her husband had undergone intensive training with Lashkar-e-Taiba -- the radical extremist group blamed for the Mumbai attacks.
Despite warnings about his activities, Headley continued to move freely, travelling to Pakistan, India, Dubai and Europe in 2006, gathering information and material that made the Mumbai attacks possible.
There were a series of other warnings about Headley both before and after that 2005 tip.