KARACHI, Pakistan -- The Pakistani Taliban threatened more violence Monday after a five-hour assault on the nation's busiest airport killed 29 people -- including all 10 attackers -- raising a new challenge for a U.S. ally trying to end years of fighting that has claimed thousands of lives.

With recently started peace efforts stalled, the cautious government of Prime Minister Nawaz Sharif may be dragged closer to a decision on whether to take on the militants in earnest across a country with a long history of ambiguity when it comes to dealing with militancy.

A further weakening of stability in the nuclear power whose tribal regions are already a hotbed of foment could ripple to neighbouring Afghanistan as international combat forces prepare to withdraw from that country.

"Everywhere is a threat," warned Interior Minister Chaudhry Nisar Ali Khan. "Every area is a target, every building is a potential target."

Such an attack in Karachi, Pakistan's business centre, will likely discourage foreign investment at a time when its economy is struggling.

The Taliban said the assault on the Jinnah International Airport in Karachi, Pakistan's largest city, was in revenge for the November killing of the militant group's leader in a U.S. drone strike.

In a telephone call to The Associated Press, the group's spokesman, Shahidullah Shahid, warned that "such attacks will continue until there is a permanent cease-fire."

The attack began late Sunday when 10 gunmen, some disguised as policemen, stormed into a section of the sprawling airport where a terminal for VIP flights and cargo is located. They opened fire with machine-guns and rocket launchers, sparking a battle with security forces that lasted until around dawn.

Heavy gunfire and multiple explosions were heard coming from the terminal amid the fighting. A major fire rose from the airport, illuminating the night in an orange glow as the silhouettes of jets could be seen.

At least some of the gunmen wore the uniform of the Airport Security Force, said an official near the terminal. All the attackers wore vests of explosives, some of which were detonated when they were shot at by the police, the official said, speaking on condition of anonymity because he was not authorized to talk to the media.

The attack started about the same time that airport security personnel and the staff from the Pakistani International Airlines engineering wing were changing shifts, said two of the PIA employees. The employees asked not to be identified because they were not authorized to speak to the media.

A cargo building was left completely gutted by the fire and the explosions, said Rizwan Akhtar, the chief of Pakistan's elite paramilitary Rangers.

Just before dawn, security forces regained control of the airport, and all 10 attackers were dead, Akhtar said. Some of the attackers appeared to be Uzbeks, he added, but officials were still investigating.

The attackers intended to destroy aircraft or possibly take people at the airport hostage, Khan said, adding that 19 people were killed. Most of the dead were airport security personnel who took the brunt of the assault.

During the battle, airport operations were suspended and all incoming flights were diverted. It reopened Monday afternoon.

Shahid, the spokesman for Tehrik-e-Taliban Pakistan -- as the Pakistani Taliban are known -- said the attack was to avenge the death of Hakimullah Mehsud, the Taliban chief who was killed in an American drone strike in November 2013.

Mehsud's death was the last major killing of a militant commander under the controversial drone program. The AP reported in May that the program has largely wound down over Pakistan, and there hasn't been a drone strike in the country since December.

The claim further diminished prospects for a resumption of peace talks with the Pakistani Taliban that officials had hoped could bring an end to the group's years-long campaign seeking to overthrow the government.

Sharif's government has advocated a policy of trying to negotiate with militants to end the insurgency, but the talks have floundered recently. The Taliban called off a cease-fire they had declared during the negotiations. Since then, Pakistani troops have hit hideouts with airstrikes in the troubled northwestern region, killing dozens of suspected militants.

But Samina Ahmed, senior adviser for South Asia from the International Crisis Group, said part of the problem is that Pakistan doesn't have a clear policy on dealing with the militancy.

"There is already a military operation," she said, referring to the airstrikes. "But that operation is reactive and tactical. It's not strategic, and it's not sustained."

If Sharif were to get serious in taking on the militants, there could be serious blowback in Pakistan, including in his home territory of Punjab province that has been relatively insulated from the violence. Many of the militant groups draw support from Punjab province, and critics question whether Sharif's party, which controls the Punjab government, has the political will to take on the militants there.

Imtiaz Gul, director of the Islamabad-based Center for Research and Security Studies, said the government has been worried about attacks on Punjab province if it pushes for a large scale military operation.

"That's one of the considerations," he said. "They believe they can develop Punjab into an island of peace and prosperity."

Karachi has been the site of previous attacks, including one in 2011 against a naval base that lasted for 18 hours and killed 10 people, deeply embarrassing the military. Security officials have been worried that a breakdown in negotiations could result in a spike in violence in Karachi, which has seen the Pakistani Taliban gain a major foothold in the city in recent years.

Santana reported from Islamabad. Zarar Khan, Munir Ahmed and Asif Shahzad in Islamabad, and Adam Schreck in Dubai contributed to this report.