Pentagon Seeks Mightier Bomb vs. Iran
The 30,000-pound "bunker-buster" bomb, known as the

Massive Ordnance Penetrator, was specifically designed to take out the hardened fortifications built by Iran and North Korea to cloak their nuclear programs.
But initial tests indicated that the bomb, as currently configured, wouldn't be capable of destroying some of Iran's facilities, either because of their depth or because Tehran has added new fortifications to protect them.
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