U.S. Secretary of Defense Robert Gates walks off his plane at Al-Assad Air Base in Iraq September 1, 2010, on a surprise visit as the the U.S. Army officially ends its combat mission in Iraq. REUTERS/Jim Watson/Pool

WASHINGTON (Reuters) - Defense Secretary Robert Gates said the unauthorized release of some 70,000 classified documents about the Afghanistan war did not reveal sensitive information, but could endanger Afghans who helped the United States, U.S. media reported Sunday.

Gates made his assessment in an August 16 letter to Senator Carl Levin, chairman of the Senate Armed Services Committee, after the website Wikileaks released the documents in July. The New York Times and CNN both were given access to the letter.

“The initial assessment in no way discounts the risk to national security,” Gates wrote. “However, the review to date has not revealed any sensitive intelligence sources and methods compromised by the disclosure.”

Gates also said disclosing the names of cooperating Afghans, who could become targets for the Taliban, could cause “significant harm or damage to national security interests of the United States.”

Wikileaks, which says it is a non-profit organization funded by human rights campaigners, journalists and the general public, came under intense criticism for releasing the Afghan war papers.