LONDON — Only weeks ago, the Pakistani Taliban appeared to be on the ropes. Violent rivalries split the insurgency in two. Peace talks with the government collapsed. Military jets pounded militant hideouts in the tribal belt.
So with a point to prove, the Taliban hit back, and on Monday it threatened to launch more attacks.
Ten militant fighters, disguised as government security forces and armed with rocket launchers and suicide vests, stormed the Karachi airport Sunday night. They came with food, water, and ammunition, in apparent preparation for a long siege but also with big ambitions: perhaps to hijack a commercial airliner, government officials said Monday, or to blow up an oil depot or to destroy airplanes on the tarmac.
Paramilitary guards pinned the fighters down in a cargo terminal, in a firefight that blazed through the night. After five hours, as stranded passengers waited anxiously in parked airplanes, it was over, with 29 people dead and the cargo building on fire. All 10 of the militants were killed.
Yet the audacious assault shook the country to its core. It showed how, despite the Taliban’s challenges and deepening divisions, their reach has extended far from their tribal redoubt into Pakistan’s biggest city.
With several jihadists from Uzbekistan among the dead, the attack also demonstrated how the Taliban can still draw on an international militant network to conduct sophisticated operations against high-profile targets across the country.
And it may be a sign of more violence to come.
“This marks an escalation of the war,” said Adil Najam, the dean of the Pardee School of Global Studies at Boston University. “And it shows that this is going to be a long war.”
The spokesman for the main Pakistani Taliban faction, Shahidullah Shahid, said as much, calling the strike in Karachi “a response to the recent attacks by the government.” And even as he said the group was still interested in talking peace with the government, he promised that, in the meantime, “We will continue carrying out such attacks.”
The chief minister of Sindh province, Syed Qaim Ali Shah, told reporters that in addition to the 10 attackers, 19 other people had died at the airport, including 11 members of the Airport Security Force, five local airline officials, and three others.
“They were well trained,” he said of the assailants. “Their plan was very well thought out.”
Major General Rizwan Akhtar, the director general of a paramilitary force that is deployed in Karachi, said the attackers appeared to be of Uzbek origin. Akhtar said the attackers came in two groups of five each. Three attackers detonated their explosive vests, while seven were killed by security forces, he said.
The assault was the most ambitious of its kind in Pakistan since Islamist militants attacked a navy air base in central Karachi in 2011.
Although elite commandos moved quickly to counter the airport assault, many Pakistanis expressed shock that militants could penetrate such a prominent target so thoroughly and raised questions about why the attack had not been prevented by the military’s powerful spy service, the Directorate of Inter-Services Intelligence.
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, Hakimullah Mehsud, in a US drone strike.
Mehsud’s death was the last major killing of a militant commander under the controversial drone program, the Associated Press reported. The program has largely wound down in Pakistan, and there has not been a drone strike in the country since December.
Pakistani officials said the escalation of insurgent violence is a potential risk for the entire country.
‘‘Everywhere is a threat,’’ warned Interior Minister Chaudhry Nisar Ali Khan. ‘‘Every area is a target, every building is a potential target.’’
Sunday’s attack could push the government of Prime Minister Nawaz Sharif closer to a decision on whether to battle the militants in earnest.
Sharif’s government has advocated a policy of trying to negotiate with militants to end the insurgency, which has continued for years, but the talks have foundered 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.
Many of the militant groups draw support from Punjab province, the home base of Sharif, and critics question whether the prime minister’s party has the political will to take on the militants there.
A further decline in security in Pakistan, which is a nuclear power, could affect the stability of neighboring Afghanistan as US troops and other international combat forces prepare to withdraw from that country. And the attack in Karachi, Pakistan’s business center, could discourage foreign investment at a time when its economy is struggling.
Karachi has been the site of previous attacks, including the 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.