Fugitive intelligence contractor Edward Snowden's theft of 1.7 million secret documents could put US military forces in "lethal" danger worldwide, American lawmakers said, citing a confidential Pentagon report.
The Defence Department sent the classified paper analysing the potential impact of revelations by the former National Security Agency (NSA) contractor to members of Congress on Monday. The report itself was not made public.
Defence Intelligence Agency chief Lieutenant General Michael Flynn formed a Pentagon task force after Snowden's theft of classified files was discovered, a DIA spokesman said on Thursday. The DIA-led task force worked with other members of the intelligence community, the military services and the combatant commands.
"The goal was to assess the potential impact to the Department of Defence from the compromise of this information," the spokesman added, speaking on condition of anonymity.
Only an initial assessment was provided to lawmakers and the task force "continues its work as additional information is reviewed", according to the spokesman.
Snowden has disclosed details of US intelligence-gathering operations, but lawmakers warned that the leaker's illegal haul included a large amount of classified military data.
"This report confirms my greatest fears: Snowden's real acts of betrayal place America's military men and women at greater risk," House Intelligence Committee chairman Mike Rogers said in a joint statement with the panel's top Democrat, Dutch Ruppersberger.
The actions by Snowden, who is in Moscow under temporary asylum, "are likely to have lethal consequences for our troops in the field", Rogers added.
Snowden and his supporters argue that his revelation of details of secret US programmes that hoover up vast amounts of telephone and internet data on virtually every American was merely a mission to defend civil liberties.
The disclosures have triggered a monumental debate in the United States over the balance between personal freedoms and fighting terrorism, but have also sparked uproar against Washington amid revelations the NSA had tapped mobile phones of world leaders, including German Chancellor Angela Merkel.
While the global media has zeroed in on the intelligence collection, the congressmen said that many documents scooped up by Snowden contained "vital" military operational details which could cause "irreparable harm" if they were obtained by the enemies of the US.
"Snowden handed terrorists a copy of our country's playbook and now we are paying the price," Ruppersberger said.
"We have begun to see terrorists changing their methods because of the leaks and this report indicates that the harm to our country and its citizens will only continue to endure."
President Barack Obama is expected to support curbs on spying on foreign leaders and is considering stripping the NSA of its ability to store telephone records of millions of Americans.
Additional reporting by Associated Press