The Federal Aviation Administration warned that attacks against US planes may happen when flights may be on the ground and during take-off or landing.
The US on Thursday issued an advisory to all its air carriers and commercial operators to exercise caution when flying into, out of, within or over the territory and airspace of Pakistan.
The advisory has been issued due to extremist or militant activities.
"The US warns its own air carriers to avoid Pakistan airspace due to risk of possible threat to attacks on US airlines (commercial and US state carriers) by Pakistan extremist and militant groups," it said.
The US Federal Aviation Administration (FAA) in a statement said the attacks may happen when flights may be on the ground and during take-off or landing.
It added that there continues to be a risk to the US civil aviation from attacks against airports and aircraft, particularly for aircraft on the ground and planes operating at low altitudes, including the arrival and departure phases of flights.
"The ongoing presence of extremist/militant elements operating in Pakistan poses a continued risk to the US civil aviation from small-arms fire and complex attacks against airports," the FAA warned.
According to the statement, there continues to be ongoing presence of extremist or militant elements operating in Pakistan which poses a continued risk from small fire, complex attacks, indirect weapons fire, any of which could occur with little or no warning.
"While, to date, there have been no reports of man-portable air defence systems (MANPADS) being used against civil aviation in Pakistan, some extremist/militant groups operating in Pakistan are suspected of having access to MANPADS," it added.
As a result, the FAA said, there is a potential risk for extremists to "target civil aviation in Pakistan with MANPADS."
The justification for this advisory will be re-evaluated by 1st January 2021.