The indictment says Scooter Libby learned about Mrs. Wilson first from a senior State Department official, then from a CIA officer, and then from Mr. Cheney himself. Diplomat, Joseph Wilson, went to Niger in 2002 at the request of the Central Intelligence Agency to investigate allegations that Iraq tried to buy uranium to make a nuclear bomb. Mr. Wilson reported back that the uranium story was unfounded. But Mr. Cheney's team kept on pushing the claim.

http://www.truthout.org/docs_2005/102905Z.shtml