US Secretary of State Mike Pompeo said he was "hopeful" Wednesday of resetting the troubled relationship with Pakistan, a key player in the Afghan conflict, after cordial meetings in Islamabad including with new premier Imran Khan.

The shift in tone comes days after Washington confirmed plans to cancel $300 million in military aid, and was echoed by Khan, who voiced his optimism at a fresh start in the long-rocky ties between the wayward allies.

The former CIA director, making his first visit as top US diplomat to Pakistan, told pool reporters shortly before leaving Islamabad that the "broad spectrum" of topics discussed included efforts "to develop a peaceful resolution in Afghanistan".

"I'm hopeful that the foundation that we laid today will set the conditions for continued success," he said -- though he added there was a "long way to go" before Washington would resume military assistance.