US vice president Joe Biden has met Pakistan leaders as part of America's efforts to get Islamabad to intensify the fight against Islamist militants sheltering along the Afghan border.
Mr Biden's one-day trip comes after the country's pro-Washington government narrowly avoided collapse last week when its coalition partners threatened to pull out.
Washington is committed to giving Pakistan 7.5 billion dollars (£4.8 billion) in aid over the next five years, aimed at improving the lives of ordinary Pakistanis and showing its military and civilian leaders that the US is its long-term friend.
The US is also asking Islamabad to step up military efforts against Taliban and al Qaida militants who use bases in north-west Pakistan to launch attacks on American and Nato troops in neighbouring Afghanistan.
Pakistan has undertaken operations in six out of its seven tribal regions close to Afghanistan and lost more than 2,000 soldiers, but has so far not moved into North Waziristan, which remains a haven for militants.
Islamabad says its forces are too stretched to attack that region at the moment.
During his stop in Afghanistan on Tuesday, Mr Biden said success there would "require more pressure on the Taliban, from Pakistan's side of the border, than we've been able... to exert so far".
US policymakers regard Pakistan as of equal, if not more importance, to America's long-term strategic interests than Afghanistan. But Washington's options are limited in dealing with the country.
While encouraging the Pakistani military to take action in the north-west, the CIA has stepped up its use of drone strikes to target militants in the borderlands over the past year.
One such strike in the North Waziristan region killed four people on Wednesday, intelligence officials said.