"The latest military intelligence data point to heightened U.S. military preparations for both an air and ground operation against Iran," the official said, adding that the Pentagon has probably not yet made a final decision as to when an attack will be launched.
He said the Pentagon is looking for a way to deliver a strike against Iran "that would enable the Americans to bring the country to its knees at minimal cost."
He also said the U.S. Naval presence in the Persian Gulf has for the first time in the past four years reached the level that existed shortly before the invasion of Iraq in March 2003.
Col.-Gen. Leonid Ivashov, vice president of the Academy of Geopolitical Sciences, said last week that the Pentagon is planning to deliver a massive air strike on Iran's military infrastructure in the near future.
A new U.S. carrier battle group has been dispatched to the Gulf.
The USS John C. Stennis, with a crew of 3,200 and around 80 fixed-wing aircraft, including F/A-18 Hornet and Superhornet fighter-bombers, eight support ships and four nuclear submarines are heading for the Gulf, where a similar group led by the USS Dwight D. Eisenhower has been deployed since December 2006.
The U.S. is also sending Patriot anti-missile systems to the region.