Secretary of State Hillary Clinton arrived in Pakistan on Wednesday promising a new page in relations and several civilian investment deals.
Here are some questions and answers about U.S.-Pakistani relations:
WHY IS PAKISTAN IMPORTANT FOR THE UNITED STATES?
Pakistani support is crucial for the United States as it strives to defeat al Qaeda, capture its leaders and bring stability to Afghanistan.
Al Qaeda leader Osama bin Laden has gone to ground since the September 11, 2001, attacks on the United States but he is believed to be hiding out somewhere along the Pakistani side of the lawless Afghan border.
Pakistan has captured and handed over to the United States numerous al Qaeda members including September 11 plotter Khalid Sheikh Mohammed.
Pakistan is attacking Pakistani Taliban militants, but the United States is pressing it to act against Afghan Taliban leaders behind surging violence there.
The commander of U.S. and NATO forces in Afghanistan, General Stanley McChrystal, said in an assessment leaked to the media last month that senior Afghan Taliban leaders were based in Pakistan and were reportedly aided by some elements of Pakistan's ISI, its main military Inter-Services Intelligence agency.
Pakistan denies that as well as a U.S. assertion that an Afghan Taliban leadership council, or shura, is based in the southwestern Pakistani city of Quetta.
WHY IS THE UNITED STATES IMPORTANT FOR PAKISTAN?
The United States is Pakistan's biggest aid donor and has given about $15 billion in direct overt aid and military reimbursements since 2002, about two-thirds of it security-related.
A new U.S. aid package triples non-military assistance to Pakistan to $1.5 billion a year over the next five years but conditions attached on various issues, including counter-terrorism and nuclear non-proliferation efforts, angered many Pakistanis including the powerful military.
Pakistan is being propped up by an $11.3 billion International monetary Fund loan. Pakistan would also like the United States to press India to resolve the core dispute between the nuclear-armed South Asian rivals over the divided region of Kashmir. India is opposed to outside involvement.
WHAT IS THE STATE OR RELATIONS?
There is suspicion on both sides and analysts speak of a trust deficit. As well as militant sanctuaries in Pakistan, the United States has worried about nuclear proliferation. Pakistan says a nuclear smuggling ring run by its top scientist was broken several years ago. The United States has expressed confidence in the safety of Pakistan's nuclear weapons.
Many Pakistanis feel the United States has blown hot and cold toward them based on its own strategic interests. The United States used Pakistan as a staging area to help supply Afghan fighters who drove the Soviet Union from Afghanistan in 1989. It subsequently largely retreated from the area, leaving many Pakistanis and Afghans feeling abandoned. Pakistan also resented U.S. sanctions over its nuclear program.
Many Pakistanis are opposed to U.S. involvement and a May 2009 poll by WorldPublicOpinion.org showed that 58 percent of Pakistanis had a very unfavorable view of the U.S. government.
Strikes by missile-firing U.S. drone aircraft on suspected militants in northwest Pakistan have also enraged many Pakistanis although some U.S. officials say the strikes are carried out under an agreement that allows Pakistani leaders to decry the attacks in public.
ANY OTHER MAIN ISSUES?
As part of its efforts to step up civilian assistance, the United States is trying to help Pakistan tackle a chronic electricity shortage. A team of U.S. officials has been in Pakistan for energy talks this week and Clinton is expected to announce some steps to help during her visit.