Pakistan and the United States have maintained a critical strategic partnership for the past 10 years despite tense relations over the war in Afghanistan and U.S. suspicions that Islamabad maintains ties to militant groups.
But the past year was a particularly difficult one for the two uneasy allies.
The deterioration of an already-fragile relationship began in January, when police in Lahore arrested, Raymond Davis, a civilian contractor working for the Central Intelligence Agency, for killing two Pakistanis.
Davis claimed ?self defense? and was ultimately released. But the incident unleashed public criticism against the Pakistani government over its oversight of CIA contractors.
Before the rift had healed, U.S. special forces conducted a unilateral raid and killed fugitive al-Qaida chief Osama bin Laden in Abbottabad, a Pakistani garrison city.
The covert raid in May plunged the relationship to a new low. Outraged Pakistani leaders, like Pakistan's foreign secretary Salman Bashir, criticized it as an attack on the country?s sovereignty.
?The fact is that the Pakistani armed forces, they had not been consulted, they were not in the know," said Bashir.
For their part, U.S. officials questioned how the world?s most-wanted man was able to evade detection for years, living near a large Pakistani military base.
Secretary of State Hillary Clinton visited Islamabad days after the Abbottabad operation to tell Pakistan the way forward for both countries was to step up joint efforts against terrorism.
"The United States and Pakistan have worked together to kill or capture many of these terrorists here on Pakistani soil," said Clinton. "This could not have been done without close cooperation between our governments, our militaries, and our intelligence agencies. But we both recognize there is still much more work required and it is urgent."
The powerful Pakistani military came under intense pressure at home for failing to detect both the presence of the al-Qaida leader and the U.S. raid that killed him.
In response, the Pakistani army ordered U.S. military trainers to leave Pakistan and tightened visa restrictions on U.S. staff. American officials in turn linked billions of dollars of financial assistance to improved cooperation in the fight against terrorism.
In late November, the relationship suffered another blow when NATO air strikes on Pakistani border posts killed 24 soldiers. Pakistan closed its borders to supplies for the U.S.-led international forces in Afghanistan, expelled American personnel from an air base used for drone attacks, and boycotted an international conference held in Germany to discuss the future of Afghanistan.
Foreign Minister Hina Rabbani Khar said parliament is now reviewing the country?s cooperation with the United States.
?I think one of the major reasons why this year has been a bad year is because there are too many gray areas in this relationship.?
Cameron Munter, U.S. ambassador to Pakistan, agreed with Khar's assertion that 2011 has been a very difficult year.
?The best way for us to deal the difficulties we have had is to be honest with each other to try to have more engagement, not less. to work together to discuss the problems we have and to see that 2012 will be better,? Munter said.
Despite the tense political situations throughout the year, educational and cultural programs have continued in an attempt to bridge the differences through more personal interactions.
But whether this kind of public diplomacy outreach can overcome the two countries' deep political conflicts remains uncertain.