Defense Secretary Robert Gates said whistleblower website WikiLeaks is morally "guilty" for its decision to release nearly 80,000 secret military documents pertaining to the Afghanistan war. 

Speaking on the Sunday news shows, Gates and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, expressed concern about the potential damage the massive leak could do, including putting Afghan informants in harm's way. 

"My attitude on this is that there are two areas of culpability. One is legal culpability. And that's up to the Justice Department and others. That's not my arena. But there's also a moral culpability. And that's where I think the verdict is guilty on WikiLeaks," Gates said on ABC's "This Week." "They have put this out without any regard whatsoever for the consequences." 

Gates said he was "mortified" and "appalled" by the release. He said the need to protect sources is "sacrosanct" and that WikiLeaks showed "no sense of responsibility." 

Mullen, speaking on NBC's "Meet the Press," said some of the United States' Afghan sources could be killed as a result of the leak. He noted that the Taliban have said they are examining the names in the reams of documents. 

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"The potential for costing us lives I think is significant," Mullen said, adding that the publication of the information could endanger people, operations and "outcomes." 

He said on CBS' "Face the Nation" that the U.S. government is trying to protect its Afghan informants in the wake of the leak. 

WikiLeaks founder Julian Assange has vigorously defended his decision to release the documents and provide information about them ahead of time to three major publications. He said last week that the documents' contents appear to show evidence of war crimes.