U.S. Secretary of State John Kerry met with Pakistan's prime minister at the start of Nawaz Sharif's four-day visit to Washington.
Sharif will meet with several members of Congress and President Barack Obama on Wednesday.
The Pakistani leader is expected to use his visit to highlight the issues that have caused friction between Washington and Islamabad in recent years.
On Sunday, Kerry said the U.S. relationship with Pakistan "could not be more important.''
But relations between Pakistan and the U.S. have been lurching from crisis to crisis.
As a sign of improvement in the ties, the U.S. has decided to release more than $1.6 billion in military and economic aid to Pakistan that was suspended when relations between the two countries soured over the covert raid that killed al-Qaida head Osama bin Laden inside Pakistan in 2011.
The Afghanistan peace process and the U.S. drone campaign against militants in Pakistan are likely to top the agenda when Sharif meets the U.S. leadership. He will also use the trip to seek help for his country's ailing economy and dysfunctional energy sector.
The U.S. seeks Pakistan's cooperation in cracking down on militants who allegedly launch attacks on U.S. and NATO troops in Afghanistan from safe havens in Pakistan.
This is Sharif's first visit to Washington since being elected the Pakistan's prime minister for a record third time last May.