Hersh writing in The New Yorker implied Washington and Islamabad made arrangements that "would allow specially trained American units to provide added security for the Pakistani arsenal in case of a crisis."
His article was swiftly refuted by U.S. and Pakistani officials who said Islamabad was fully capable of protecting its nuclear arsenal.
"Our security apparatus has the capacity and is fully geared to meet all conceivable challenges, therefore we do not need to negotiate with any other country to physically augment our security forces, which in any case, we believe, are more capable than their forces," said Gen. Tariq Majid, chairman of the joint chiefs of staff for the Pakistani military.
Hersh in an interview with Newseye, a Dawn television news program, downplayed the claims, saying he had referred to an "informal understanding" between top U.S. and Pakistani military generals.
He warned, however, that the Pakistani nuclear arsenal was threatened not only by Taliban insurgents, but also by the potential for a military coup against the civilian government.
U.S. Secretary of State Hillary Clinton in October said that while militants certainly threatened the authority of Islamabad, Washington has "confidence in the Pakistani government and military's control over nuclear weapons."