Pentagon chief Chuck Hagel has held talks with Pakistani Prime Minister Nawaz Sharif as Washington sought to defuse tensions over controversial US drone strikes and Islamabad's role in Afghanistan.
In the first visit by a US defence secretary in nearly four years, Hagel flew from Kabul to Islamabad to meet the premier and the country's new army chief, General Raheel Sharif.
Ties between Washington and Islamabad have been seriously strained over US drone strikes in Pakistan's tribal belt as well as Afghan Taliban sanctuaries inside Pakistan's borders.
Prime Minister Sharif "reaffirmed Pakistan's support for the Afghan peace and reconciliation process," a Pakistan government statement said.
"The Prime Minister also conveyed Pakistan's deep concern over continuing US drone strikes, stressing that drone strikes were counter-productive to our efforts to combat terrorism."
President Barack Obama has defended the drone strikes as an effective, lawful tool used with restraint to target suspected Al-Qaeda militants.
But human rights groups and Pakistani politicians say the missile attacks have killed innocent civilians and must stop.
After greeting Prime Minister Sharif, Hagel said Pakistan and neighbouring Afghanistan had a "lot of common and mutual interests" and that he looked forward to discussing regional issues.
Hagel was in Pakistan "in recognition of the tremendous support that Pakistan has provided in the war on terror", a senior US defence official told reporters.
The defence secretary wanted to affirm continued US military assistance, the official said.
"There is some friction in the relationship", and Hagel wished to tackle that "head on", he added.
The visit came as Hagel's deputies withdrew Sunday's statement that said NATO shipments out of Afghanistan through Pakistan were to resume due to the end of anti-drone protests.
In recent weeks, activists opposed to the drone raids forcibly searched trucks in northwest Pakistan in a campaign to disrupt NATO supply routes through the Torkham gate border crossing.
The club-wielding protesters have prompted US officials to halt the shipments to protect truck drivers ferrying NATO equipment.
Contractors were still concerned over anti-drone protests and the suspension had not been lifted, officials travelling with Hagel said.
Torkham gate is the main overland route used by the Americans and NATO to withdraw military hardware from Afghanistan as part of the troop pullout set to wrap up by the end of 2014.
US officials are anxious to forge a constructive dialogue with Pakistan's new army chief General Raheel Sharif, who is expected to be at the centre of sensitive security decisions.
"Issues concerning (the) defence relationship, Pak-US bilateral ties and regional stability came under discussion," the Pakistan military said after Hagel met the army chief.
Since 2002, Washington has given Pakistan more than $16 billion in security assistance and "coalition support funds", US officials said.
Pakistan is seen as crucial to peace in neighbouring Afghanistan as it was a key backer of the hardline 1996-2001 Taliban regime in Kabul and is believed to shelter some of the movement's leaders.
