(CNN) -- WikiLeaks founder Julian Assange said Friday that he was disappointed by criticism from Secretary of Defense Robert Gates over the release of about 76,000 pages of U.S. documents related to the war in Afghanistan.
Gates said Thursday that the massive leak will have significant impact on troops and allies, revealing techniques and procedures.
Assange rejected that assessment Friday, saying in a release that Gates "has overseen the killings of thousands of children and adults" in Afghanistan and Iraq.
Adm. Mike Mullen, chairman of the U.S. Joint Chiefs of Staff, also criticized Assange and the person who gave him the documents. WikiLeaks, Mullen said, was risking lives to make a political point.
"Mr. Assange can say whatever he likes about the greater good he thinks he and his source are doing, but the truth is, they might already have on their hands the blood of some young soldier or that of an Afghan family," Mullen said Thursday at a Pentagon news conference.
Gates said he asked that the FBI help the Pentagon in its investigation of who might have leaked the documents to Assange's internet site.
An Army private suspected of leaking classified material, including videos and other documents, has been transferred from Kuwait to a Marine Corps brig in Quantico, Virginia.
Pfc. Bradley Manning, who served as an intelligence analyst in Iraq, was charged in June with eight violations of the U.S. Criminal Code and is the military's focus in the investigation into who gave thousands of documents to WikiLeaks.
Manning, 22, will remain in confinement as the Army continues the investigation to determine whether he should face the military equivalent of a trial over the charges, according to an Army statement Thursday.
Assange has refused to say where his whistle-blower website got about 91,000 United States documents about the war. About 76,000 of them were posted on the site Sunday in what has been called the biggest leak since the Pentagon Papers about the Vietnam War.
Assange's statement Friday was harshly critical of Gates, particularly over deaths in Afghanistan.
"Secretary Gates could have used his time, as other nations have done, to announce a broad inquiry into these killings," the statement said. "He could have announced specific criminal investigations into the deaths we have exposed. He could have announced a panel to hear the heartfelt dissent of U.S. soldiers, who know this war from the ground. He could have apologized to the Afghani people.
"But he did none of these things. He decided to treat these issues and the countries affected by them with contempt. Instead of explaining how he would address these issues, he decided to announce how he would suppress them.
"This behavior is unacceptable. We will not be suppressed. We will continue to expose abuses by this administration and others."