Adm. Mike Mullen, who's chairman of the Joint Chiefs of Staff, says the U.S. is duty-bound to try to shield informants who were named in the documents.
Taliban spokesmen have said that their organization will use the material to try to hunt down people who've been cooperating with what the Taliban considers a foreign invader.
The website WikiLeaks posted nearly 77,000 secret documents a week ago, leading to wide condemnation from U.S. officials.
Mullen was interviewed on CBS' "Face the Nation" and NBC's "Meet The Press."
