The Obama administration has delayed payment of hundreds of millions of dollars in promised military aid and reimbursement to Pakistan to reflect its displeasure with that country’s lagging security cooperation, according to U.S. and Pakistani officials.

The decision to withhold the aid follows Pakistan’s cancellation of visas for more than 100 U.S. Special Operations trainers working with that country’s Frontier Corps, along with its refusal to issue visas for equipment technicians, after long-escalating bilateral tensions culminated in the cross-border U.S. raid in May that killed Osama bin Laden.

Pakistan’s actions “have given us reason to pause,” White House Chief of Staff William M. Daley said Sunday on ABC’s “This Week.” “Until we get through these difficulties, we’ll hold back some of the money that the American taxpayers have committed to give.”

The withheld aid is worth about $800 million, including a payment of $300 million for reimbursement of Pakistani counterinsurgency expenditures. The money, part of what Pakistan says is more than $1 billion owed on the account, was approved by the Defense Department several months ago but has not been disbursed.

U.S. equipment approved for the Frontier Corps, which is based in the tribal regions where Taliban and al-Qaeda havens are located, also has been withheld, including “ISR [intelligence, surveillance and reconnaissance] gear, explosive ordnance disposal support and equipment, small arms and ammunition, and other soldier kit,” said a senior U.S. military official who spoke on the condition of anonymity about the classified action.

Delivery of additional items to the Pakistani military — night-vision goggles, helicopter spare parts, communications gear and counter-explosive equipment — also has been suspended.

U.S. officials said that in the case of some of the equipment, there was no point in sending it to Pakistan if U.S. trainers and technicians were not there to instruct local troops in its use. The officials indicated that the shipments would resume if the visa questions and other issues were resolved.

Pakistan has long complained about slowness of U.S. payments and equipment deliveries. A senior Pakistani military official suggested Sunday that the U.S. trainers have been unnecessary from the start of the nearly three-year-old program and that the Americans wanted a military presence on the ground as an “excuse to shape and influence behavior” within Pakistan’s armed forces.

“We don’t need trainers,” the official said, noting that the Pakistani military has trained the troops of more than a dozen nations. “We need the equipment. . . . These are all games.”

The U.S. decision, which was initially reported by the New York Times on Saturday evening, marks the first time that aid has been purposely withheld in response to Pakistani actions. Assistance to Pakistan last year totaled nearly $4.5 billion, more than half of which went to the military.

The bin Laden raid has heightened long-standing tensions on both sides, angering and humiliating the Pakistani military, which was not informed in advance about the operation because U.S. officials feared the information would be leaked. The Obama administration and many lawmakers questioned how bin Laden could have lived for years in a Pakistani garrison city without some official knowledge or support.

U.S. officials have long said that militant sanctuaries in the tribal areas operate with the complicity of at least some elements of Pakistan’s intelligence service.

In a series of recent visits, top U.S. national security officials, including Secretary of State Hillary Rodham Clinton and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, made specific demands of Pakistan for more cooperation.

The results have been mixed. Pakistan has given the CIA access to bin Laden’s residential compound and has allowed interviews with individuals at the compound who were taken into custody. After first refusing new visas for CIA personnel, Pakistan has approved dozens of them.

But an experiment in shared intelligence failed last month when information given to the Pakistanis about the location of several Taliban and al-Qaeda weapons factories in the tribal areas resulted in an apparent tip-off to militants, who evacuated the sites before the arrival of Pakistani military units.

Last week, Mullen publicly implicated Pakistan in the June kidnapping, torture and death of a local journalist who was critical of the intelligence service. Pakistan called the accusation “baseless” and “irresponsible.”

Pakistan has repeatedly said that it is the United States, particularly the CIA, that should be faulted for not sharing intelligence. In a statement issued Sunday, one day after  Defense Secretary Leon Panetta said al-Qaeda leader Ayman al-Zawahiri is hiding in Pakistan’s tribal areas, that nation’s army suggested that it had not been told about his whereabouts. “We expect the U.S. intelligence establishment to share available information and actionable intelligence” regarding al-Zawahiri and other top terrorism targets, the statement said. 

The administration has tempered its criticism of Pakistan with an acknowledgment that its cooperation is crucial to the U.S. war effort in Afghanistan.

“It’s not failed,” Daley said of the bilateral relationship. “The truth of the matter is, our relationship with Pakistan is very complicated. Obviously, they’ve been an important ally in the fight on terrorism. They have been the victim of enormous amounts of terrorism.

“But while the Pakistani relationship is difficult,” he added, “it must be made to work over time.”

Both sides are under extreme domestic pressure to stand firm. Pakistan’s army chief, Gen. Ashfaq Kayani, has been openly jeered by junior officers demanding that he not make concessions to the Americans. U.S. popularity in Pakistan, already low, has nose-dived amid escalating demands that the CIA stop the drone attacks that the Obama administration considers its most effective weapon against Pakistan-based militants.

Some U.S. lawmakers, meanwhile, have called for cuts in assistance. In the defense spending bill it approved last week, the House included requirements that the administration ensure that counterterrorism money given to Pakistan is being properly spent.

“We understand there is a lot of discussion and debate” in Washington over the U.S.-Pakistan relationship and that the Defense Department is “slowing things down to make sure their point of view” is being fully understood in Islamabad, said a second Pakistani official, who is supportive of close ties between the two nations.

“But the government of Pakistan has not been told of any aid cutoff,” the official said. “To the contrary, we have been told the administration is working very hard” to persuade Congress not to cut aid.

Staff writer Karin Brulliard in Islamabad, Pakistan, contributed to this report.