At least three persons were shot dead and 12 others injured during clashes between security forces and staff of Pakistan International Airlines (PIA) protesting at Karachi's international airport
No group has yet claimed responsibility for the attack, which forced flights at the Bacha Khan International Airport in Peshawar to be temporarily suspended.
At least 430,000 people have fled the region into nearby areas of Pakistan as well as neighbouring Afghanistan, the biggest movement of refugees in Pakistan in years.
Six missiles were fired targeting a compound and a vehicle parked inside it in the Dargah Mandi area, a security official said. Five militants were killed in the attack, the official said.
At least 10 militants were killed on Tuesday during airstrikes in Pakistan's North Waziristan region.
But the large military operation could spark a wave of bloody reprisal attacks, especially in Karachi or Peshawar, where militants already have a sizeable presence.
The Taliban's main stronghold is in the North Waziristan tribal district, where the Pakistan military began its offensive on Sunday night.
The strikes are the first in the nuclear-armed South Asian nation since an attack in December last year in which three suspected militants were killed.
The Taliban is most likely to rely on small militant teams, emulating the protracted, high-impact operations like those in Mumbai in 2008 and Nairobi's Westgate mall last year.
Sixteen militants were killed in in two US drone strikes within last 24 hours in Pakistan's restive tribal region, ending a five-month hiatus.
The focus of the probe is a vehicle which reportedly dropped the militants near the gate of the old terminal of the Jinnah International airport.
It is clear that Pakistan is facing a backlash of the terror network that it at one stage help grow.
Tracking the latest updates from the shocking attack on Pakistan's busiest airport, the Jinnah international airport in Karachi.
"We have offered assistance to the relevant Pakistani authorities investigating this heinous crime," a State Department spokesperson told PTI.
The Pakistani Taliban threatened more violence on Monday after a five-hour assault on the nation's busiest airport killed 29 people, including all 10 attackers.
At least 30 people, including 10 terrorists, were killed before security forces today eventually regained control over the key facility in Pakistan's financial capital.
The Karachi airport attack is the latest in a series of Pakistan-specific fidayeen attacks. But terror outfits change both targets and tactics overnight. This presents a scary picture for India.
The militants attacked the Jinnah International Airport late last night, resulting in a six-hour gun battle with security forces involving army, paramilitary Rangers, police and Airport Security Force.
The assault will raise fresh concerns about Pakistan's shaky security situation, and questions about how militants were able to penetrate the airport, which serves one of the world's biggest cities.
Equipped with suicide vests, grenades and rocket launchers, they battled security forces in one of the most brazen attacks in years in Pakistan's biggest city.