Robert Gates warns against attack on Iran Iranian soldiers march during the annual military parade on September 21, 2012 in front of the mausoleum of the Iran's late leader Ayatollah Khomeini in Tehran, Iran. The parade marks the beginning of the 1980-1988 war between Iran and Iraq. UPI/Maryam Rahmanian NORFOLK, Va., Oct. 4 (UPI) -- Former U.S. Secretary of Defense Robert Gates said a military attack on Iran could "prove catastrophic." Gates -- who headed the Pentagon during the administration of former President George W. Bush and remained at the post when Barack Obama became president -- said America and Israel lack the capability to wipe out Iran's underground facilities permanently, and an unprompted attack would ensure a nuclear Iran eventually, after the country digs its labs deeper underground and redoubles its resolve, the (Norfolk, Va.) Virginian-Pilot reported Thursday. "The results of an American or Israeli military strike on Iran could, in my view, prove catastrophic, haunting us for generations in that part of the world," Gates said Wednesday in a speech in Norfolk. He urged U.S. diplomats to make clear Israel does not have a "blank check" to attack Iran unilaterally. Instead, Gates said the United States and Israel should pursue economic sanctions and international isolation, which he said will convince Iranian leaders to abandon their nuclear ambitions.