ISLAMABAD: When US President Barack Obama inherited Washington's partnership with Pakistan, he kept the money flowing in hopes that stronger ties would help end the Afghan war and give Pakistan more tools to keep its nuclear arsenal from falling into extremists' hands. What Washington has gotten for its billions, however, is limited progress on clearing militant strongholds on the Afghan-Pakistan border and a souring relationship that included threats this month to limit CIA drone strikes and require Pakistani clearance for Washington spy operations. Adding to the complications is the narrow nature of the relationship. America's interests in Pakistan – transformed by the 9-11 attacks – are built almost entirely around high-stakes security issues and the bonds between the CIA and Pakistan's spy agency. Washington expects its massive aid to Pakistan should buy it broad cooperation and wide latitude to strike at Islamic militants, including those backing the Taliban in Afghanistan. But in Pakistan, there are growing calls to rein in US operations, particularly in the wake of a bitter diplomatic dispute after a CIA contractor fatally shot two Pakistanis in January. Pakistan also sees the US alliance in practical terms: a way to keep pace with rival India and prop up its flagging economy. “Ultimately, both sides will suffer an unhappy relationship because we oddly need each other,” said Christine Fair, assistant professor at the Center for Peace and Strategic Studies at Georgetown University in Washington, who closely follows Pakistan's military and intelligence affairs. “They need our money and our weapons to keep up with India and to maintain their rentier state economy,” she added. “We need them because we are scared about their nuclear weapons, the militants and the intersection of the two.” Both sides make no secret of their gripes. Pakistan is frustrated by stepped up drone attacks and accusations it is weak against militants despite nearly 3,000 dead soldiers, a five-year war in its tribal areas and dozens of arrests of suspected Al-Qaeda operatives or affiliates. Washington grumbles that Taliban-backed groups still find sanctuaries in Pakistan and other hard-line factions – some with links to Al-Qaeda – are growing in strength. Obama's policies also are on the line. He abandoned the US protocol of engaging almost solely with Pakistan's military. He chose instead to embrace a costly program of support for Pakistan's civilian political system, expecting it would lead to efforts to wipe out domestic extremists. In Pakistan, newspapers express near daily outrage over an “arrogant” America allowed to kill Pakistanis with impunity and pulling the strings of the weak government of President Asif Ali Zardari. But it was the arrest of CIA contractor Raymond Davis that exposed the fissures in the critical relationship between CIA and Pakistan's intelligence agency, known by the acronym ISI. Western officials familiar with the events said there were heated exchanges between the CIA and ISI when Pakistan refused to consider him covered by diplomatic immunity and release him immediately. ISI Director Gen. Shuja Pasha even temporarily severed communications with the CIA, according to a Western diplomat who asked not to be identified because it would compromise his relationship with the ISI. The fallout, however, may not be over. Georgetown analyst Fair said both countries are studying how to move forward in a relationship with “starkly divergent strategic interests.” “Both sides wonder if the other is a pain-in-the-ass ally or an outright foe,” she said. “This conversation is happening on both sides.”