WASHINGTON -- WikiLeaks is at least morally guilty for releasing classified US documents on the Afghanistan war, Defense Secretary Robert Gates said yesterday, as investigators broadened their probe of the leak.

The whistleblowing Web site published tens of thousands of war records a week ago, a move the Pentagon has said could cost lives and damage the trust of allies by exposing US intelligence-gathering methods and names of Afghan contacts.

"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," Gates told the ABC News show "This Week with Christiane Amanpour."

Defense Secretary Robert Gates blasts WikiLeaks yesterday on "This Week with Christiane Amanpour," saying the revelation of secret information puts the lives of US soldiers in peril.

"But there's also a moral culpability. And that's where I think the verdict is 'guilty' on WikiLeaks. They have put this out without any regard whatsoever for the consequences."

Gates and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, appeared on television talk shows renewing those concerns amid fears WikiLeaks may publish more documents.

The release of the documents has fanned doubts about President Obama's strategy to turn the tide in the unpopular war. July, with 66 fatalities, was the deadliest month for US forces in Afghanistan since fighting there started in 2001.

Mullen, speaking on NBC's "Meet the Press," called the leak "unprecedented" in its scope and volume. He said the Pentagon is trying to protect Afghans who may be at risk of Taliban retaliation following the publication of the secret war documents.

"People that aren't in a fight like this, that don't do this for a living, don't understand what the potential is for something like this in terms of the kind of information, and a piece of information may seem very innocent in and of itself, and a lot of this is old information," he said.

The Taliban has said it will use the material to try to hunt down people who've been cooperating with the United States.

The investigation into the leak is focusing on Pfc. Bradley Manning, who worked as an Army intelligence analyst in Iraq. Manning is already under arrest and charged with leaking a classified video showing a 2007 US helicopter attack that killed a dozen people in Iraq, including two Reuters journalists.

Adrian Lamo, a former computer hacker who reported Manning to authorities this year after receiving what appeared to be incriminating messages from him, told Reuters he believed probers are looking at people close to Manning with ties to WikiLeaks.

Lamo also said Manning was aided by two students at MIT who passed along encryption software, CNN reported.

Manning, being held at a detention facility in Virginia, has not been officially named as a suspect in the latest leak.

Obama, in an interview taped Friday and broadcast yesterday, said the goal for the Afghanistan war is modest enough to achieve.

The president said the United States isn't trying to turn Afghanistan into what he calls a "model of Jeffersonian democracy." The goal, Obama told CBS's "Sunday Morning" show, is to keep Afghanistan from returning to being a terrorist haven.