Nonetheless, senior lawmakers say they have no doubt that Pakistan is aiding insurgent groups. “The burden of proof is on the government of Pakistan and the ISI to show they don’t have ongoing contacts,” said Senator Jack Reed, a Rhode Island Democrat on the Armed Services Committee who visited Pakistan this month and said he and Senator Carl Levin of Michigan, the committee chairman, confronted Pakistan’s prime minister, Yousaf Raza Gilani, yet again over the allegations.

Such accusations are usually met with angry denials, particularly by the Pakistani military, which insists that the ISI severed its remaining ties to the groups years ago. An ISI spokesman in Islamabad said Sunday that the agency would have no comment until it saw the documents. Pakistan’s ambassador to the United States, Husain Haqqani, said, “The documents circulated by WikiLeaks do not reflect the current on-ground realities.”