The United States appears to have widened drone aircraft attacks against al Qaeda-linked militants in their Pakistani safe havens as it struggles to stabilise Afghanistan, Pakistani and US officials say.
So far 20 strikes have been carried out by the remotely piloted US drones in September, the record number in a month.
While no high-value militants were reported killed, Pakistani intelligence officials say a number of low-ranking ones from different nationalities are believed to have died.
"We are not surprised at this surge because we knew that as Americans build up their presence in Afghanistan, they will intensify pressure on the militants on both sides of the border and these attacks are part of the same strategy," a senior security official told Reuters.
"It appears that they have lowered their threshold and are hitting every militant irrespective of his ranking in al Qaeda, the Taliban, the Haqqani network," he said.
US President Barack Obama ordered in an extra 30,000 troops for Afghanistan late last year, the last units of which arrived this month.
Most recent drone strikes in Pakistan targeted the Haqqani faction. Named after veteran mujahideen leader Jalaluddin Haqqani, the group closely linked to al Qaeda is now led by his son Siraj.