Pakistan’s army chief warned Thursday that any repeat of the type of U.S. commando operation that killed Osama bin Laden would be viewed as a violation of Pakistani sovereignty and would imperil military and intelligence cooperation between the two countries.

The combative statement came as a senior U.S. defense official said Pakistan would have to take “very concrete and visible steps” to persuade Congress to continue providing $3 billion in annual military and economic assistance.

“We are still talking with the Pakistanis and trying to understand what they did know, what they didn’t know” about bin Laden’s apparently years-long residence in a garrison city north of the Pakistani capital, Defense Undersecretary Michele Flournoy said at the Aspen Institute in Washington.

Obama administration officials said they were uncertain whether the statement by Gen. Ashfaq Kayani, which also acknowledged “shortcomings” in Pakistani intelligence on bin Laden, reflected Pakistan’s actual stance or whether it amounted to posturing for a domestic audience.

In conversations with U.S. officials, one administration official said, Kayani had been “much more nuanced. . . . We didn’t hear this bellicosity.”

Regardless of the statement’s intended audience, it reflected the intense anger felt at the highest levels of Pakistan’s powerful military toward the United States and suggested that the two countries remain far apart in how they view bin Laden’s killing.

The discovery of the terrorist leader’s refuge deepened belief in Washington that elements of Pakistan’s army had provided him sanctuary. But Pakistan’s military and intelligence establishment has chafed at U.S. expressions of victory and shown acute resentment about what it deems a lack of gratitude for Pakistan’s partnership.

The administration has asked Pakistan for details about the compound where bin Laden lived in Abbottabad and who had access to it. But officials have largely refrained from criticizing Pakistan in recent days while trying to keep a crucial, if unsteady, counterterrorism partnership from completely unraveling.

“It is not always an easy relationship,” Secretary of State Hillary Rodham Clinton said Thursday in Rome, on the sidelines of an international conference on Libya. “But, on the other hand, it is a productive one for both of our countries, and we are going to continue to cooperate.”

At White House meetings Wednesday, President Obama’s national security advisers discussed how long to wait before delivering a sterner message to Pakistan, what it should be and who should deliver it, the administration official said. One option under consideration is for Vice President Biden, who visited with Pakistani President Asif Ali Zardari in January, to make a phone call. Another is to wait until Clinton visits Islamabad, the Pakistani capital, later this month.

“We realize that at this point we have a great degree of leverage, and we want to make sure we use it wisely and effectively, because it won’t last long,” said the official, who was not authorized to discuss the situation on the record.

Doubts on both sides

The Thursday statement was the first by Kayani since the bin Laden operation. In the statement, he and Pakistan’s other top generals said they had decided to reduce U.S. military personnel in the country to the “minimum essential.” But U.S. military officials said they had received no formal request to draw down the 120 Special Operations trainers presently working in Pakistan.

Kayani’s statement described Pakistan’s Inter-Services Intelligence agency as second to none in combating terrorism and its CIA counterparts as untrustworthy.

“In the case of Osama bin Laden, while the CIA developed intelligence based on initial information provided by ISI, it did not share further development of intelligence on the case with ISI, contrary to the existing practice between the two services,” the statement said, adding that Pakistani spies had captured or killed about 100 al-Qaeda operatives and leaders.

U.S. officials have long alleged that elements of Pakistan’s intelligence establishment provide support to Islamist militants as assets for influence against archenemy India. U.S. officials have said this week that they have no evidence of state support in Pakistan for bin Laden, but they have also expressed deep doubts that he could have lived in a military town without assistance from some security officials.

Those doubts were voiced Thursday at a hearing on Pakistan held by the Senate Foreign Relations Committee. At the hearing, virtually all members questioned what Pakistan knew and did about bin Laden. “Some critics say it is time for us to wash our hands of the whole country,” said Sen. Richard G. Lugar (Ind.), the ranking Republican on the committee. He said his view was that “distancing ourselves from Pakistan would be unwise and extremely dangerous.”

Lugar, John F. Kerry (D-Mass.), the committee chairman, and Rep. Howard L. Berman (D-Calif.) co-sponsored a $7.5 billion, five-year package of economic assistance to Pakistan in 2009. On Thursday, Berman sent Clinton a letter questioning whether Pakistan was qualified to receive the aid, as she had certified in March.

Earlier Thursday, in the Pakistani government’s first detailed briefing on the bin Laden killing, Foreign Secretary Salman Bashir appeared to question the legality of the U.S. operation. Pakistani media have speculated that the United States, riding high, would soon try to capture Afghan Taliban leader Mohammad Omar or the chief of the Haqqani network, another Afghan militant group.

Issue of sovereignty

At least on the surface, the Pakistani responses indicate that Washington might not be able to easily leverage the embarrassing revelation that bin Laden was hiding in plain sight in Pakistan to force the nation’s army to hit harder against militant sanctuaries, turn over other high-value terrorists living in Pakistan or help speed reconciliation in Afghanistan.

But in a week in which Pakistan’s army and intelligence services have faced a rare onslaught of criticism, the Pakistani statements also appeared to reflect a concerted effort to redirect the public discourse toward anger at the United States. Violations of sovereignty, particularly by U.S. troops, are a sensitive issue in Pakistan, and the national conversation has begun to focus on that, rather than on the presence of militants in Pakistani cities.

Pakistanis “feel deeply angered, aggrieved, and humiliated at the failure of our civil and military leadership in the face of the flagrant violation of our sovereignty by the government of the United States,” said a statement Thursday from the Pakistan Ex-Servicemen Association, an organization of about 2,000 former officers.

The army promised an investigation into how bin Laden could have lived undetected in Pakistan. But past Pakistani government and military inquiries, including into the assassination of former prime minister Benazir Bhutto, have rarely been revealing.

Staff writer Walter Pincus in Washington contributed to this report.