Last week's U.S. raid into Pakistan is fueling one of the country's most enduring—and potentially dangerous—conspiracy theories: that the U.S. has designs on Pakistan's nuclear arsenal and is prepared to send highly trained commandos into the country to seize control of the weapons.

The pervasive Pakistani belief that the U.S. would be willing and able to effectively steal the country's nuclear weapons helps explain Islamabad's surprisingly aggressive official response to the Navy SEAL assault that killed Osama bin Laden, the world's most wanted terrorist.

Gen. Ashfaq Kayani, the head of Pakistan's armed forces, released a blistering public statement late last week condemning the U.S. assault and warning that he would order his troops to use armed force against any American troops who entered Pakistan in the future in pursuit of other wanted militants.

Kayani's statement also made explicit reference to his country's nuclear arsenal, which he promised to fully defend against any potential American-led efforts to take control of the weapons.