The US has spent Trillions on stealth tech and there already exist countermeasures for this. Iran has bought this technology from Ukraine and other unspecified countries. An F-117 nighthawk was shot down by Yugoslavian SA-3 Goa missile (70's technology) over Kosovo in 1999. It is 2011 and Iran possesses a lot more modern hardware than the former Yugoslavian army ever had. Anyone thinking that posturing,warmongering threats of bunker busters , sanctions or anything else will scare the Iranians, is day dreaming. Remember Iraq; they had been under sanctions for a very long time and yet it actually took boots on the ground for regime change. Iran is in a much better position than Iraq was and the only country that could put boots on the ground the USA won't do it under Obama. The Persians will get their nukes, the world will have to live with it and life will go on.
U.S. confirms ISIS computer expert killed in air strike (Reuters)
from the article: Report: U.S. Air Force receives new 15-ton bunker buster bombs