A militant splinter group that broke from the Pakistani Taliban last year and declared allegiance to Islamic State announced on Thursday it was rejoining the Taliban insurgency, a move that could be prompted by fears of isolation amid possible Afghan peace talks.
Afghan officials announced last month they were exploring possible peace talks with the Afghan Taliban although no firm dates for formal meetings were set.
Pakistani officials also announced their support for the talks, underlining warming relations with Afghanistan's new president after years of distrust under the previous regime.
Pakistani and Afghan insurgents have long had bases either side of the border, benefiting from the hostility between the governments of the two neighboring countries.
The Afghan and Pakistani Taliban are two separate groups that are loosely allied and share similar hard-line ideologies, each fighting to topple the governments of their home countries and set up an Islamist theocracy.
Now Pakistani insurgents are becoming increasingly worried about being squeezed between a hostile Pakistani military and a potentially inhospitable Afghanistan, said Saifullah Mahsud of the FATA Research Center.
"They are all in the same boat. It makes more sense for them to join hands rather than fight the Pakistani army alone," Mahsud said.
Jamaat-ul-Ahrar split from the Pakistani Taliban last summer amid leadership rivalries. The splinter group launched a series of devastating suicide attacks and later announced its allegiance to the Islamic State group, a move that Mahsud said signaled frustration over waning support from an embattled al-Qaida and hope that Islamic State might send men or money.
So far, there have been few signs that Islamic State has provided significant support to Pakistani or Afghan groups.
Jamaat-ul-Ahrar announced its decision to rejoin the Pakistani Taliban in a press release from spokesman Ehsanullah Ehsan. Another militant group, Tehreek-e-Lashkar-e-Islam, is also joining the main Taliban insurgency, the statement said.
That group, already sympathetic to the Taliban, is led by Mangal Bagh and has its main strength in Khyber Agency and the hotly contested Tirah valley, one of the main smuggling routes into Afghanistan.
"This blessed decision was taken by the leaders of all the three jihadi groups," the statement said. "We warn the followers and defenders of the infidel democratic system of Pakistan that in any situation we will not let the conspiracies of the [infidel] Pak Army ... succeed."
In June, Pakistan's military launched an operation to drive the Taliban from their bases in the remote mountain region of North Waziristan, along the Afghan border.
This year, the military also began hanging convicted militants, following the massacre of 134 schoolchildren and 19 adults in the northwestern city of Peshawar in December.
The statement said four Taliban prisoners who had been hanged were "martyrs" and vowed revenge on the military.