"Exercise caution during flight operations. There is a risk to US civil aviation operating in the territory and airspace of Pakistan due to extremist/militant activity," said the US Federal Aviation Administration in a notice to airmen (NOTAM) dated December 30, 2019.
The NOTAM is applicable to all US-based airlines and US-based pilots.
The US regulator said in its NOTAM that there continues to be a risk to US civil aviation sector from attacks against airports and aircraft in Pakistan, particularly for aircraft on the ground and aircraft operating at low altitudes, including during the arrival and departure phases of flights.
"The ongoing presence of extremist/militant elements operating in Pakistan poses a continued risk to US civil aviation from small-arms fire, complex attacks against airports, indirect weapons fire, and anti-aircraft fire, any of which could occur with little or no warning," it said.
The FAA said that while, to date, there have been no reports of man-portable air defense systems or Manpads being used against the civil aviation sector in Pakistan, some extremist or militant groups operating there are suspected of having access to these Manpads.