WASHINGTON — When Secretary of State Hillary Rodham Clinton met Pakistan’s president at the NATO summit meeting in Chicago last week, the two spent most of the meeting talking politics, and Mrs. Clinton was nothing if not blunt.


President Asif Ali Zardari complained about the difficulties of unifying Pakistan’s fractious political parties to support a more aggressive campaign against extremists and noted it was an election year in both countries.


“We don’t have the resources or control over these groups,” he said, referring to militants based in Pakistan’s borderlands. He added, “We’re backed into a corner because you haven’t apologized” for a NATO attack in November that killed 24 Pakistani soldiers at an outpost on the border with Afghanistan.


Reflecting the Obama administration’s mounting frustration, Mrs. Clinton told him that the only way countries have defeated insurgencies like the ones threatening Pakistan and its neighbor was by forging national unity and exercising political will.


“It’s going to take leadership,” she told a subdued Mr. Zardari, according to officials from both countries familiar with the hourlong meeting at McCormick Place last Sunday. “It’s going to take leadership from you and others.”


Mr. Zardari’s visit to the summit meeting — after an 11th-hour invitation intended as a conciliatory gesture — went well for neither the United States nor Pakistan. It not only failed to resolve a six-month deadlock over the transportation of supplies to Afghanistan, but it also underscored the poisonous distrust and political chasms in an uneasy alliance that is central to the Obama administration’s plan to end the war in Afghanistan.


“You have to look at the meeting in context of whether it’s worth the investment having Pakistan as a partner,” one Obama administration official said bitingly. The best that that official could say of Mrs. Clinton’s meeting with Mr. Zardari was that it was “not a total waste” since she was able to deliver such a pointed message.


Far from moving toward some kind of easing of tension, relations have only worsened since then. On three days last week, American drones fired missiles at what were thought to be insurgent hide-outs in northwestern Pakistan, ending a brief lull heading into the NATO summit meeting and ignoring demands by Pakistan’s Parliament to end the strikes altogether. And on Wednesday, a court in Pakistan convicted a doctor who helped the C.I.A. in the search for Osama bin Laden, sentencing him to 33 years in prison for treason.


The next day the Senate approved a new cut of $33 million in American military assistance to Pakistan, $1 million for each year of his sentence.


The failed diplomacy of the last week highlighted the inability of both countries to repair a relationship that was badly frayed by the secret raid that killed Bin Laden in May of last year and then was nearly ruptured by the NATO attack in November. It has raised questions over whether even a more limited security relationship between the two countries is even possible.


“It’s an up-and-down relationship,” Defense Secretary Leon E. Panetta said Sunday on ABC’s “This Week.”


Officials from both countries expressed a desire to resolve their differences, but it appeared that both were drifting ever farther apart. “We need to scale back expectations for each other,” Sherry Rehman, Pakistan’s ambassador to the United States, said in an interview.


For Mr. Zardari, the visit to Chicago was a political disaster at home, exposing the increasingly embattled president to blistering criticism. In a clear diplomatic slight, President Obama refused to hold a meeting with him, speaking to him for only a few minutes on the way to a group photograph of the world leaders who came to Chicago to map out an end to the war in Afghanistan.


While Mr. Obama later expressed support for “a successful, stable Pakistan,” he added, “I don’t want to paper over the differences there.”


In Pakistan, Imran Khan, a former cricket star who has become one of the most popular opposition leaders, declared the visit a disgrace to the country, and accused the United States and NATO of ignoring the demands of its Parliament and its own sacrifices in the fight against terrorists. “This is not our war,” Mr. Khan said of Afghanistan, “so let’s get out of it.”


The tensions over Afghanistan, over Pakistan’s perceived unwillingness to strike against insurgents within its borders and over the continued American drone strikes have resisted a year of efforts to ease them. Mrs. Clinton has now met Mr. Zardari three times since the Bin Laden raid; after the first two she had expressed hope that the relationship was “back on track,” as she put it in Islamabad in October.


After Pakistan’s Parliament completed a review of relations with the United States in April, Mrs. Clinton and others in the State Department expected that they could reach a new understanding on security cooperation, which has been more or less delayed since November. A series of American delegations visited officials in Pakistan — led by Deputy Secretary of State Thomas R. Nides and Marc Grossman, the administration’s special envoy — only to find Pakistan changing its demands in response to domestic politics and, some said, Mr. Zardari’s weakened position.