images of flag-draped coffins on TV, and widespread outcry from Pakistanis incensed by the US air attack that killed 24 of their soldiers on the Afghan border last November.
The breakthrough, in which Islamabad reopened supply routes into Afghanistan and Washington yielded to months of Pakistani demands to apologize for the border deaths, was praised as a prelude to improved ties between two nations whose security alliance had lapsed into mutual suspicion and hostility.
After US secretary of state Hillary Clinton's discussions with Pakistani President Asif Ali Zardari in the cavernous Chicago conference center where world leaders met for a Nato summit, Clinton instructed Thomas Nides, a top deputy back in Washington, to do what it took to find a solution ensuring Nato could once again supply the war in Afghanistan via Pakistan.
At the heart of last week's denouement was a carefully worded statement that allowed the United States to accommodate Pakistani indignation without opening President Barack Obama up to criticism months before presidential polls.
Just as importantly, it aimed to avoid alienating those within Obama's government who had resisted apologizing to a country many in Washington see as acting to subvert US goals in the region, even while accepting massive US aid.
"A lot of people were holding their nose at the White House and the Pentagon at the notion of an apology," a US official said on condition of anonymity.
"The logic was that this was not a full-throated apology but that it was enough of a statement of regret, using terms associated with an apology, to get us across the GLOC finish line," the official said, using the acronym used for the supply routes - or Ground Lines of Communications - that Pakistan shut down after the November 26 border attack.
"It was a semantic high-wire act."
Taking it to the top
Clinton's talks in Chicago with Zardari proved pivotal because, for the first time, they elevated months of efforts to hammer out a solution on technical issues, including proposed fees on Nato supplies, to the senior political level.
Nides and his Pakistani counterpart, finance minister Abdul Hafeez Shaikh, then spent weeks crafting language that would be acceptable to both sides, sealing the deal during Nides' visit to Islamabad just days before an internal US deadline of the July 4 independence holiday.
Without a deal, US officials believed, fed-up lawmakers might act to clamp down on US aid to Pakistan after then.
In her statement, issued after a call last Tuesday with Pakistani foreign minister Hina Rabbani Khar, Clinton did not use the word "apology."
"Foreign minister Khar and I acknowledged the mistakes that resulted in the loss of Pakistani military lives," Clinton said.
"We are sorry for the losses suffered by the Pakistani military," she said.
According to sources familiar with the matter, the deal was aided by signals from the Pakistani side that parliamentary demands for an "unconditional" apology would not necessitate stronger language than Clinton ultimately used. Pakistan also dropped demands for extra fees on Nato supplies.
In what may have been another instrumental element, Pakistani officials said the linguistic hair-splitting in Washington would fade when Clinton's statement was translated into Urdu.
After months of rejecting an apology, the White House appears to have embraced the final arrangement in the latter part of June as bipartisan support emerged in Washington for striking a deal.
US officials saw political reaction to Defense Secretary Leon Panetta's June 13 congressional testimony - in which he said that the supply route closure was costing an extra $100 million a month - as a meaningful sign that an apology wouldn't trigger a political storm for Obama.
There were also suggestions that patience was growing short among Washington's Nato allies, who began to signal interest in unilateral arrangements of their own with Pakistan.
Another US official said that while France and Britain - British foreign secretary William Hague made a visit to Islamabad in mid-June - expressed eagerness to have the ground routes open, there was never any suggestion that fellow Nato nations would break ranks with the United States.
Reservations at Pentagon
Clinton's language appeared to have been crafted with one eye on the US Defense Department, where officials for months had refused to apologize for a confused nighttime incident that they saw as a case of legitimate self-defense: the Pakistanis, they said, fired first.
A US investigation into the incident - in which Pakistan refused to take part - found that both sides were to blame and said the deaths were the result of a "misunderstanding." Pakistan called it an unprovoked assault.
Importantly, Pakistan's military could scarcely afford to be seen as bowing to the United States just months after coming under unprecedented public pressure for the 2011 US raid, conducted without Islamabad's knowledge, that killed al Qaeda leader Osama bin Laden on Pakistani territory.
While the state department advocated some sort of apology from the start, resistance by many officials at the Pentagon and White House was magnified by widespread frustration at Pakistan's perceived unwillingness act against militants, something seen as a top impediment to stability in Afghanistan as Nato nations withdraw their troops.
Pakistan vehemently denies turning a blind eye to insurgents and points out that many of its own soldiers and civilians have died at the hands of various militant groups.
At the Pentagon, both Panetta and General Martin Dempsey, chairman of the Joint Chiefs of Staff, were known to be strongly opposed to an apology. As late as June 21, Panetta suggested past expressions of regret and condolence were sufficient.
"We've made clear what our position is, and I think it's time to move on," Panetta said in an interview with Reuters, when asked if he would oppose a further apology.
Last week, Panetta welcomed the reopening of the supply routes in a two-sentence statement, saying the two countries would work together on security issues. There was no mention of the Pakistani soldiers who died.
Panetta "has acknowledged the regrets we expressed ... and the mistakes made by both sides," said Captain John Kirby, a Pentagon spokesman. "And he has been clear that it is time to move the relationship forward."
While the position of the US defense chief and others at the Pentagon many not have changed since November, they do not appear to be troubled by the wording of the message that broke the long impasse with Pakistan.
"Everyone at the end of the day can say they got what they wanted - the White House, the Pakistanis, the state department, the Pentagon," the first US official said.