The United States does not possess conventional armament powerful enough to destroy Iran's deeply hidden nuclear facilities, U.S. officials told the Wall Street Journal late Friday.
American Defense Secretary Leon Panetta also confessed that Pentagon is not strong enough to destroy Iran's nuclear facilities.
Washington was "still trying" to develop more powerful bombs, he claimed.
Late last year, Bloomberg reported that the U.S. Air Force received new 15-ton bombs capable of destroying deep underground bunkers.
However, speaking to the Wall Street Journal on Friday, U.S. officials estimated that even the 15-ton bombs would not be powerful to put a full stop to Iran's nuclear program, either because of some of the facilities' depth or their newly added fortifications.
One unnamed officials said Pentagon analysts estimated that currently held conventional bombs would not be effective against Iran's enrichment plants, especially the underground ones.
"Once things go into the mountain, then really you have to have something that takes the mountain off," the official told the Wall Street Journal.