The Chicago man charged with helping plot the terror attacks one year ago in Mumbai also photographed and conducted surveillance of a nuclear weapons fuel plant in Tromboy, India, according to Indian and U.S. law enforcement authorities.
The authorities say David Headley was sent to Tromboy, a northwest suburb of Mumbai, by his handlers in the terror group Lashkar-e-Taiba, an affiliate of al Qaeda.
The Bhabha Atomic Research Center in Tromboy is capable of producing 66 pounds of plutonium a year for four the country's nuclear weapons, according to David Albright of the Institute for Science and International Security.
"You would have had one helluva international crisis if they had taken control of the facility and caused some kind of accident with a serious release of radioactive material," said Albright.
"There have always been questions about India's nuclear security and because it's located on the water and not far from Mumbai, it would be a logical target," added Albright.
Headley is accused by federal authorities of conducting the pre-operational surveillance of the Mumbai hotels that were stormed by Lashkar-e-Taiba gunmen last November 26.
In a criminal complaint unsealed earlier this month, authorities said Headley took boat trips in the Mumbai harbor to find landing sites for the 10-man commando team that carried out the attacks. More than 170 people were killed.
The Pakistani-born American citizen travelled to Mumbai five times between 2006 and 2008, posing as an American Jew with a new video camera, according to U.S. officials.
Headley's role in the planning of a possible attack on the nuclear facility came to light after the FBI arrested him in connection with the hotel attacks and another planned attack on a Danish newspaper which had published cartoons mocking Allah.
The FBI recently briefed Indian authorities about their investigation of Headley's activities, including the connection to the nuclear facility.
The impact of such an attack would depend on the quality of the attacking force and their objective, said Lt. Steve Margolis of the Los Angeles Police Department, the former head of the department's anti-terror unit.
"It depends on what they were trying to achieve. Were they intending immediate panic, were they intending creating a loss of confidence in India's nuclear program? Were they looking for potential release / exposure?," said Margolis.
In addition to the surveillance at the nuclear facility, authorities say Headley also plotted bus routes used by scientists and senior military officials to and from an Indian war college.