The Pentagon is speeding up delivery of a colossal bomb designed to destroy hidden weapons bunkers buried underground and shielded by 4,535 kilograms of reinforced concrete.
Call it Plan B for dealing with Iran, which recently revealed a long-suspected nuclear site deep inside a mountain near the holy city of Qom.
The 15-tonne behemoth, called the "massive ordinance penetrator," or MOP, will be the largest non-nuclear bomb in the US arsenal and carry 2,400 kilograms of explosives. The bomb is about 10 times more powerful than the weapon it is designed to replace.
The Pentagon has awarded a nearly USD 52 million contract to speed up placement of the bomb aboard the B-2 Stealth bomber, and officials say the bomb could be fielded as soon as next summer.
Pentagon officials acknowledge that the new bomb is intended to blow up fortified sites like those used by Iran and North Korea for their nuclear programs, but they deny there is a specific target in mind.
"I don't think anybody can divine potential targets," Pentagon press secretary Geoff Morrell said. "This is just a capability that we think is necessary given the world we live in."
The Obama administration has struggled to counter suspicions lingering from George W Bush's presidency that the US is either planning to bomb Iranian nuclear facilities itself or would look the other way if Israel did the same.