Pakistani warplanes are practising landing and taking off on highways as part of a military exercise known as "Highmark", which comes amid high tensions with neighbouring India. Several scheduled passenger flights have been cancelled at the last minute in northern Pakistan due to closure of the airspace.
Close to two dozen flights, which were supposed to use the airspace between the midnight of 21 September and 22 September post-noon, remain suspended. Most of these were Pakistan International Airlines (PIA) flights.
Earlier, a press release was issued on the closure of two major highways near Peshawar and Lahore in the region citing "construction work".
Local media reports speculate the drill is directly aimed at a potential threat from India, which witnessed a major extremist attack recently. Eighteen Indian soldiers were killed when Pakistan-based militants stormed an army base in Indian-administered Kashmir's Uri.
The Inter-Services Public Relations (ISPR) and the Pakistan Air Force's media arm are tight-lipped on the exercise leading to more speculation. A senior military official told the Pakistani daily Dawn on condition of anonymity that "extreme vigilance" is being exercised given the current standoff with India.
Speculation is rife about the possibility of India launching surgical strikes or military action but officials from both India and Pakistan have sternly ruled out any such thing. The Indian defence ministry strongly denied a report by Indian news website Quint, which said 20 Islamists were killed and over 200 injured, when two units of Indian forces entered Pakistani territory to conduct a strike. The story cited anonymous military sources and some of the details were not substantiated.