Each year on Jan 17, Shahana bakes a cake and invites friends to her home in Peshawar. They sing happy birthday for her son, even light a candle. But it’s a birthday without the birthday boy.

Her son, Asfand Khan, was 15 in December 2014 when gunmen rampaged through his military-run Army Public School in Peshawar killing 150 people, most of them students, some as young as five. Asfand was shot three times in the head at close range.

The attackers were Pakistani Taliban, representing the proscribed Tehreek-i-Taliban Pakistan (TTP), who seven years later have once again ramped up their attacks, seemingly emboldened by the return of Afghanistan’s Taliban to power in Kabul.

TTP regroups

In the last week of December, they martyred six Pakistani army personnel over two attacks, all in the country’s northwest.

Read more: Four soldiers martyred in gun battle with terrorists in North Waziristan: ISPR

The TTP is regrouping and reorganising, with its leadership headquartered in neighbouring Afghanistan, according to a UN report from July. These developments are raising alarm among Pakistanis like Shahana of a return of the horrific violence the group once inflicted.

While the Afghan Taliban have said their soil won't be used to attack other countries and also rejected TTP's claim of being a "branch of IEA", they have shown no definitive signs of expelling TTP leaders, even as Pakistan leads an effort to get a reluctant world to engage with Afghanistan’s new rulers and salvage the country from economic collapse.

What will Kabul do?

It is a dilemma faced by all of Afghanistan’s neighbours and major powers like China, Russia and the United States as they ponder how to deal with Kabul.

Multiple militant groups found safe haven in Afghanistan during more than four decades of war, and some of them, like the TTP, are former battlefield allies of the Afghan Taliban.

China fears insurgents from its Uighur ethnic minority who want an independent Xinjiang region, which shares its border with Afghanistan. Thus, Beijing fears Afghan soil could be used as a staging ground by separatists.

Russia and Central Asian nations worry about the Islamic Movement of Uzbekistan, which in recent years went on a recruitment drive among Afghanistan’s ethnic Uzbeks.

The TTP, meanwhile, poses a problem for Pakistan. The group perpetrated some of the worst terrorist assaults in the country, including the 2014 assault on APS Peshawar.

The TTP numbers anywhere from 4,000 to 10,000 fighters, according to the UN report.

A resurging threat

"It [TTP] has also succeeded in expanding its recruitment inside Pakistan beyond the former tribal regions along the border where it traditionally found fighters," says Amir Rana, executive director of the Pakistan Institute of Peace Studies, an Islamabad-based independent think tank.

Analysts say the Afghan Taliban’s reluctance to clamp down on the TTP does not bode well for their readiness to crack down on many other groups.

“The plain truth is that most of the terrorist groups operating in Afghanistan, aside from IS, are Taliban allies,” says Michael Kugelman, deputy director of the Asia Programme at the Washington-based Wilson Center.

“And the Taliban aren’t about to turn their guns on their friends, even with mounting pressure from regional players and the West.”

The militants’ presence complicates Pakistan’s efforts to encourage international dealings with the Afghan Taliban in hopes of bringing some stability to an Afghanistan sliding into economic ruin.

A collapse would bring a flood of refugees; Pakistan might be their first stop, but Islamabad warns that Europe and North America will be their preferred destination.

Islamabad attempted to negotiate with the TTP recently, but the effort fell apart. Rana says Pakistan’s policy of simultaneously negotiating with and attacking the TTP is “confusing” and risks emboldening like-minded insurgents in both countries.

It also worries Pakistan's allies, he adds.

"China, which is spending billions in Pakistan, was not happy with Islamabad’s attempts at talks with the TTP because of its close affiliation with Uighur separatists," says Rana.

The TTP took responsibility for a July bombing in the upper Kohistan district of Khyber Pakhtunkhwa that killed Chinese engineers as well as an April bombing at a hotel in Quetta where the Chinese ambassador was staying.

Even if Pakistan were to ask the Afghan Taliban to hand over TTP leaders, it shouldn’t expect any results, says Bill Roggio, editor of the Long War Journal which tracks global militancy.

“The Afghan Taliban will not expel the TTP for the same reasons it won’t expel Al Qaeda,” he says.

“Both groups played a key role in the Afghan Taliban’s victory. They fought alongside the Afghan Taliban and sacrificed greatly over the past 20 years.”