U.S. intelligence believes that the secret Iranian nuclear facility acknowledged by Iran this week is in an underground tunnel complex on a military base controlled by the elite Revolutionary Guards. The details were included in a document that Obama administration sent to U.S. lawmakers. Excerpts were provided to The Association Press by an official on condition of anonymity because the document, though unclassifed, was confidential. The document says the facility is 'too small to be viable for the production of fuel for a nuclear power reactor, but may be well suited for a military purpose.' The location at the military base would also undermine Iran's claim that the program is for civilian purposes. U.S. intelligence indicates that Iran was installing centrifuge equipment this year. 