The Islamic State group is increasing its presence in Pakistan, recruiting Uzbek militants, attracting disgruntled Taliban fighters and partnering with one of Pakistan’s most violent sectarian groups, according to police officers, Taliban officials and analysts.

Its latest atrocity was an attack Saturday on a Sufi shrine in southwestern Pakistan that killed at least 50 people and wounded 100 others. The group said in a statement that a suicide bomber attacked the shrine with the intent of killing Shiite Muslims and issued a picture of the attacker.

When IS circulated a photograph of one of the attackers in last month’s deadly assault on a police academy in southwestern Baluchistan province, two Taliban officials told The Associated Press that the attacker was an Uzbek, most likely a member of the Islamic Movement of Uzbekistan. More than 60 people, most of them police recruits, were killed in that Oct. 26 attack when three assailants battled security forces for hours before being killed or detonating their suicide vests.

The Taliban officials, both of whom are familiar with the IMU, spoke on condition of anonymity because their leadership has banned them from talking to the media.

Authorities initially said the police academy attack was orchestrated by militants hiding out in Afghanistan and blamed Pakistan’s virulently anti-Shiite group, Lashkar-e-Jhangvi. But IS later claimed responsibility and Lashkar-e-Jhangvi spokesman Ali Bin Sufyan said they partnered with IS to carry out the assault.

In Afghanistan and Pakistan, the extremist group has adopted the name the Islamic State in Khorasan — a reference to an ancient geographical region that encompassed a vast swath of territory stretching from Turkmenistan through Iran and Afghanistan.

IS in Khorasan has set up its base in Afghanistan’s eastern Nangarhar province, and while it has pledged allegiance to the Islamic State group in Syria and Iraq, it remains unclear whether there are direct operational or financial links between the two.

According to police, Afghan officials and IS media outlets, the majority of Islamic State fighters in Afghanistan are Pakistani nationals, mostly from the tribal regions. Disgruntled Taliban fighters from Pakistan and Afghanistan have joined along with foreign fighters, mainly from central Asia. The group’s leader until his death in July in a drone strike was Hafiz Saeed Khan, a former Pakistani Taliban commander. IS has never acknowledged Khan’s death, which was confirmed by both the Afghan and U.S. militaries.

Counterterrorism officials in Pakistan say that IS has begun reaching out to local militants through its rich social media presence.

“They are inspiring the like-minded youth in Pakistan through their strong social media propaganda,” said Junaid Sheikh, a senior counterterrorism commander in the southern city of Karachi.

“There is evidence that militants of other organizations like Lashkar-e-Jhangvi, Al-Qaeda in the Subcontinent and other Sunni extremist organizations switched their ideology toward Daesh and acted like their activists,” he said, using an Arabic acronym for IS. The recruitment of Uzbek militants is particularly worrisome and a “significant threat to our national security,” he added.

He said Uzbek fighters have carried out numerous major attacks in Pakistan, including a 2011 attack on a naval base and a 2014 attack on the Karachi Airport. Local militant groups provided the intelligence to carry out the attacks, he said.

A resident of Afghanistan’s Nangarhar province who did not want to be identified for fear of retribution said he spoke with two Iranian Islamic State members late last year. Unlike the Pakistani and Afghan insurgents, the resident, who fled to Pakistan after his home was overrun by IS fighters, said the foreign fighters were friendly and engaged with local residents. One Iranian fighter said he was recruited for his computer skills, the resident said.

Previously, Uzbek insurgents normally allied with the Pakistani and Afghan branches of the Taliban, having sworn allegiance to Taliban founder Mullah Mohammed Omar. However, many Uzbek fighters split from the Taliban and declared allegiance to IS last year after it was revealed that Taliban officials had hidden the fact that Mullah Omar had died two years earlier.

A senior police official in Pakistan’s eastern Punjab province, where several militant groups are headquartered, said the IS group is firmly entrenched in Pakistan and its roots are growing stronger as it aligns with Pakistan’s Sunni Muslim extremist groups like Lashkar-e-Jhangvi. The police official spoke on condition of anonymity because he was not authorized to speak to the media. The official also said that Lashkar-e-Jhangvi had largely relocated from Punjab to Baluchistan province in the face of a major military campaign.

“Pakistani Taliban factions that have sparred with the parent Pakistani Taliban have tended to express public support for ISIS,” said Michael Kugelman, senior associate for South Asia at the U.S.-based Wilson Center. “I could certainly envision collusions materializing between disaffected Pakistani Taliban fighters now aligned with ISIS, and Uzbek militants with preexisting ties to the Pakistani Taliban. Either way, at the end of the day, all of these terrorists are cut from the same cloth ideologically and so we should never rule out operational partnerships.”

(AP)