The killing of Osama Bin Laden marks the beginning of the end of America's war in Afghanistan. That's why it's especially worrisome that already troubled US-Pakistani relations are about to be tested as never before. President Obama's determination to begin a move toward the exits in Afghanistan was known well before Sunday. He pledged many months ago that troop withdrawals would begin this July, and though the pace of drawdown remains subject to change, an administration personnel shuffle last week signaled that the president is ready to turn the page. Defense Secretary Robert Gates will retire June 30. His replacement, current CIA director Leon Panetta, is reported to be skeptical that American troops can build lasting stability in Afghanistan at an acceptable cost. In addition, Gen. David Petraeus, the US commander in Afghanistan, will replace Panetta at the CIA, so the man most committed to a long-term US troop presence in that country will now be working from Langley, Virginia. The result is a national security team that may be more favorably inclined to arguments that Defense Department budget cuts are a higher priority than extended support for Hamid Karzai's government in Kabul. Troop withdrawals, increasingly popular with a war-weary public and both Democratic and Republican lawmakers, still pose a political danger for Obama ahead of next year's election by opening him to charges that he lacks toughness and resolve. But the killing of Bin Laden provides a potent response. The second significant change we'll see now that Bin Laden is dead is a sharp deterioration in US relations with Pakistan. The debate will continue in Washington over how Pakistan's security services and government could have not known that Bin Laden was living in a custom-built fortress just 35 miles north of Pakistan's capital. We may never have the answer, but it's clear that for this high-risk mission, the Obama administration had zero confidence in their reliability. Washington did not inform Pakistan of the operation to kill Bin Laden until the US helicopter carrying his body had left Pakistani airspace. Forced to choose between deceit and incompetence to explain its failure to uncover Bin Laden's whereabouts, Pakistan's security services, the ISI, have chosen incompetence. To deflect charges that ranking officials within the ISI are playing both sides in America's war on Al-Qaeda and the Taliban, Pakistani diplomats remind anyone who will listen that in 2003, it was Pakistan that arrested Khalid Shaikh Mohammed, the senior Al-Qaeda leader often described as the architect of the Sept. 11 attacks. That defense won't slow momentum in Washington for an investigation of Pakistan's complicity with Al-Qaeda and a review of the billions of dollars in civilian, government and military aid that Washington sends to Islamabad each year. There's nothing new about US suspicion of Pakistan's commitment to US antiterrorism efforts, but the Obama administration has lately been unusually outspoken on the subject. Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, has visited Pakistan more than two dozen times to work with Pakistani Gen. Ashfaq Kayani to overcome decades of mutual suspicion, a mistrust that began to crest with the US invasion of Afghanistan in 2001. Following a visit to Pakistan two weeks ago, Mullen made headlines with a charge that Pakistan's intelligence community has “a long-standing relationship” with a militant network that is “supporting, funding, training fighters that are killing Americans.” Kayani dismissed the charge as “negative propaganda.” Accusations of support for a militant group that few Americans have heard of are one thing; charges of harboring Osama Bin Laden in a suburb of Islamabad are quite another. Most senior US officials understand that when it comes to combating Islamic militancy in South Asia, US-Pakistani relations are too big to fail. When President Obama's chief counterterrorism adviser, John Brennan, went before cameras on Monday to discuss the killing of Bin Laden, he refused to accuse Pakistan of anything and noted that since 9/11, Pakistan has captured or killed more terrorists than any other country. Others have noted that Pakistan is itself a constant target of murderous Islamist militants. Aware that the American media and some American lawmakers won't be so understanding, officials on both sides have jumped into damage control. Pakistani President Asif Ali Zardari penned an op-ed for Tuesday's Washington Post that reaffirms Pakistani support for American counterterrorism efforts. The chairman of the Senate Foreign Relations Committee, John Kerry, pronounced himself “encouraged” by Pakistani statements on the matter. But others on both sides will fan the flames. The former Pakistani president Pervez Musharraf on Monday called the killing of Bin Laden a “positive step,” but then charged that the US operation had violated Pakistan's sovereignty. The Democratic Senator Frank Lautenberg called for an immediate suspension of up to $3 billion in aid to Pakistan “until Congress and the American public are assured that the Pakistani government is not shielding terrorists.” Senator Susan Collins, a Republican, argued for “more strings attached to the tremendous amount of military aid” that Washington sends to Islamabad. This is a dangerous game. As US forces prepare to leave Afghanistan, Pakistan's role in the region and its willingness to target Islamic militants will become more important than ever. Killing Osama Bin Laden required no help from Pakistan, but that should not persuade anyone in Washington that Pakistan is not a crucial partner in America's ongoing struggle with Islamic militants. — The New York Times (The writer is president of Eurasia Group and author of “The End of the Free Market: Who Wins the War Between States and Corporations?”) __