Carr said the U.S. military was stunned to discover that so much material had been given to the anti-secrecy website. The disclosures comprised more than 700,000 documents, including combat strategies, State Department cables and terrorism detainee assessments.
"There was nothing about [the] WikiLeaks [situation] that was normal," said Carr, who spent much of his 31-year military career directing Army intelligence-gathering operations.
Releasing so much classified material, he said, put countless people at risk. "It's a nasty world," Carr said. "In some cases, lives will be harmed." But Carr did not specify anyone who was harmed by Manning's disclosures.
Carr said sources of information dried up and "quit talking to us as a result of the releases." He said some countries began registering complaints after reading the detainee assessments for terrorism suspects held at the U.S. military prison at Guantanamo Bay, Cuba.
In addition, he said, U.S. supply lines were compromised.
Carr left the Army in 2011 after running the Pentagon's equivalent of the CIA. He previously oversaw intelligence-gathering efforts during the Gulf War and in Bosnia, and for the wars in Iraq and Afghanistan.
When the Pentagon learned in 2010 of the "magnitude" of the disclosures, Carr said, the secretary of defense formed an Intelligence Review Task Force with Carr as its head, to weigh soldier safety, national security and foreign alliances. Often Carr reported directly to the secretary of defense.
"These were our documents that we had in our possession securely for a long period of time, and now all of a sudden this massive amount of material is available to the public and our adversaries," Carr said.