US Secretary of State Hillary Clinton arrived in Islamabad on Friday in a surprise visit amid frayed relations with the US nuclear-armed ally after the death of Osama bin Laden.
The discovery of the al Qaeda leader in a garrison town just 50 km away from the capital Islamabad raised fresh doubts about Pakistan being a reliable partner in the US-led war on Islamist militancy.
The Pakistan government welcomed the death of the al Qaeda leader but has criticised the US secret mission in Abbottabad, where bin Laden lived for years, as a breach of its sovereignty.
Many US lawmakers, skeptical that Pakistani officials did not know of bin Laden's presence, want to cut US aid to Pakistan, which the White House views as vital to counter-terrorism and to hopes of stabilising neighbouring Afghanistan.
In a sign of deepening distrust, Pakistan has told the United States to halve the number of military trainers stationed in the country.
But just a day before coming to Pakistan, Clinton said working with Pakistan was a strategic necessity for the United States, even as she pressed Islamabad to act more decisively to counter-terrorism.
She praised Pakistan as a "good partner" in global efforts to fight terrorism, though she acknowledged that the two countries have disagreed on how hard to fight al Qaeda, Afghan Taliban fighters and other militants.
"We do have a set of expectations that we are looking for the Pakistani government to meet but I want to underscore, in conclusion, that it is not as though they have been on the sidelines," she told a news conference in Paris on Thursday.
"They have been actively engaged in their own bitter fight with these terrorist extremists."