Washington (CNN) -- The release of secret documents by WikiLeaks has had a negative impact on Defense Department operations as people and governments hold back information, fearing their identities will be revealed, the Pentagon said Tuesday.
Col. Dave Lapan, Pentagon spokesman, said the documents provide potentially dangerous information to U.S. enemies.
"We do know, from various means that we have, that our adversaries are out there actively mining this for information," Lapan said in a midday off-camera question session at the Pentagon. "We have knowledge that our adversaries are out there using this information but how exactly they are changing their tactics is hard to quantify."
Lapan also said the leaks already have changed dealings between the United States and its friends and allies. "We do get a sense there has been some pulling back because of these revelations," he said. "We have gotten indications that there is at least some change in how individuals and governments cooperate with us and share information."
Last week, Defense Secretary Robert Gates said that the WikiLeaks document dump would have only "fairly modest" consequences on U.S. international policy.
Lapan took a stronger line on potential risks.
"How do you quantify information that our adversaries have gotten that have taught them things about how we operate. How do you quantify some of the other damaging elements ... learning about our TTP's (tactics, techniques and procedures), learning about how we gather information and intelligence, altering their behavior because of things they have learned," Lapan said. "Those are all real dangers that we believe have occurred but it's hard to again quantify."
The spokesman had no comment on the arrest of WikiLeaks founder, Julian Assange, in Britain on Tuesday. "I don't have a comment here. Obviously the arrest in the UK is connected to the warrant in Sweden, independent of anything the U.S. Department of Justice or the Attorney General has talked about, is undertaking," Lapan said.