The officials who described the decision said it would affect the Pakistani Army and special operations troops supported by the United States that have conducted offensives against Taliban fighters in the Swat Valley and South Waziristan in the past year, the officials said. But the process is not over: some additional Pakistani units may yet be denied American aid, officials say.

The Leahy Amendment, a law that stretches back more than a decade, requires the United States to cut off aid to foreign militaries that are found to have committed gross violations of human rights. It has been applied in the past to Indonesia and Colombia, but never to a country of such strategic importance to the United States as Pakistan.

“I told the White House that I have real concerns about the Pakistani military’s actions, and I’m not going to close my eyes to it because of our national interests in Pakistan,” Senator Patrick J. Leahy, the author of the amendment, said Wednesday from his home in Vermont. “If the law is going to have teeth, it has to be taken seriously. Pakistan’s military leaders have made encouraging statements about addressing these issues, but this requires more than statements.”

The United States spends about $2 billion a year on the Pakistani military, including money specifically designated for counterterrorism operations.

A senior Pakistani official who has been involved in discussions about the issue said the United States had conveyed its concerns about reports of extrajudicial killings, which he said Pakistan was addressing. But he said Pakistan had not been notified that any army units had been refused training or equipment. The United States government “has not threatened us with withholding of assistance or training for any of our military units on these grounds,” the official said.

Much of the administration’s review has been overseen by Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, who has also been one of the administration’s direct contacts with General Kayani. Admiral Mullen has spoken to senior lawmakers, including Senator Leahy and Senator John Kerry of Massachusetts, the chairman of the Foreign Relations Committee, and assured them that the law would be followed, a senior military said.

Once strictures are in place, the government has inspections to make sure that the sanctioned units do not receive American training or equipment.