Late one night in May, the commanders of five dormant militant factions affiliated with al-Qaeda and the Afghan Taliban gathered for a rare meeting of their shura, or leadership council, in a crime-ridden slum of Karachi, a bustling Pakistani port city of more than 20 million people.

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Grimly sipping hot tea around a low table in a dimly lit room, this was the first time the shura bosses had assembled since 2014, when the Pakistani military’s counter-terrorism campaign drove them underground. This unusual meeting of battle-hardened veterans of the blood-stained years of the 1990s was prompted by an emergency: the growing lure of Islamic State (IS) for once-loyal al-Qaeda-Taliban fighters.

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Three militants belonging to the various affiliates of the Pakistani Taliban Movement (known as the TTP, the initials of its Urdu language name) and its allied al-Qaeda affiliates had told their comrades they were planning to switch loyalties to IS, and were summoned by the shura to explain.

“They all had the same story to tell,” the head of the shura, who goes by the nom de guerre of Rafiquddin, told This Week in Asia.

After the fall of the Taliban, they tried to transition back to civilian life but found it difficult to make a living. As their job applications continued to be rejected outright by employers, they tried their hands at odd jobs and street vending, but got nowhere. “IS approached them and offered them funding and weapons, and they were desperate,” said Rafiquddin.

An alarmed shura ordered a headcount and discovered that 31 members of its affiliated factions had formally defected to IS on June 3. These defections were the first direct poaching of Pakistani al-Qaeda militants by IS since January 2015, when it announced the formation of its ‘Khurasan governorate’ for Afghanistan and Pakistan.

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Prior to that, IS was limited to the Afghan province of Nangarhar, where some 3,000 militants from the TTP and Afghan Taliban had regrouped after being driven out by the military from their erstwhile strongholds in Pakistan’s Federally Administered Tribal Areas adjoining Afghanistan.

The Sunni terror group’s swelling ranks of Pakistani militants – who share its hatred of Shia Muslims – is alarming not only for al-Qaeda and the Taliban, but for China too, given the country’s extensive business interests abroad and the fragile security of its restive Xinjiang (新疆) province.

The primary target for IS is Balochistan, Pakistan’s vast, sparsely populated western state bordering southern Afghanistan and Iran. Balochistan is the hub of the ambitious China-Pakistan Economic Corridor (CPEC) programme which, at US$46 billion (HK$356.8 billion), is the single largest component of President Xi Jinping’s ( 習近平 ) One Belt, One Road initiative of improving China’s connectivity with its neighbours.

The deadly blast this week in Quetta, provincial capital of Balochistan, that claimed at least 70 lives once again brought home the rising IS-related terror risks in the region and the danger it poses for Chinese interests.

“Balochistan provides IS with an opportunity to not only strike at Pakistani interests, but also those of China and Iran,” said Arif Rafiq, fellow at the Centre for Global Policy, a Washington think tank.

“Anti-state jihadis in Pakistan have previously sought to target Chinese citizens in Pakistan, knowing that this would strain relations between Beijing and Islamabad. Jihadis in Balochistan who’ve made the switch from al-Qaeda to IS are on a similar mission.”

The scale of the threat was evident on Monday when a suicide bomber detonated an explosives-filled jacket at a hospital in Quetta. In telephone calls made to local journalists, a spokesman for the regional chapter of Islamic State claimed responsibility for the attack, as did the Pakistani Taliban.

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The suicide bombing at the hospital was set up by the assassination earlier in the day of the president of the Balochistan Bar Association, Anwar Kasi. As mourners were gathering outside the emergency ward of the Quetta civil hospital to take his body for burial, the terrorists struck for maximum impact.

The bulk of the investment by Chinese state corporations in Balochistan are in nuclear and gas power plants. The centrepiece of CPEC is, however, the Gwadar port in western Balochistan, located close to the border with Iran. The economic corridor aims to link Gwadar with Xinjiang via highways in western Balochistan and northern Pakistan, along which Chinese-operated free trade zones are to be established.

Militant sources said early IS outreach activity had been focused near Gwadar. The recruitment of erstwhile ethnic Baloch al-Qaeda militants there has enabled IS to gain access to the safe houses and human smuggling networks operated by separatists and Karachi-based criminal gangs, they said. “There has been movement of ethnic Baloch jihadis from al-Qaeda’s network to IS,” said Rafiq.

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The Pakistani authorities have consistently downplayed the threat posed by IS, saying the latter lacks an active independent network. Instead, Islamabad accuses the Afghan and Indian intelligence services of instigating separatists to destabilise Balochistan and derail CPEC. After Monday’s blast, for example, Balochistan Chief Minister Sanaullah Zehri quickly shifted responsibility to India’s intelligence agencies rather than accept the IS and Pakistani Taliban claim.

The Pakistani authorities are taking no chances with the security of Chinese workers arriving to work on the CPEC projects. About one per cent of the programme’s overall cost, or about US$460 million, is to be spent on security, the CPEC project director, retired Major General Zahir Shah, told a Pakistani Senate committee in July.

Some 9,000 active military personnel are being recruited to provide an armed military guard for each Chinese worker involved in CPEC, backed up by 6,000 civilian security personnel.

But given IS’ recent attempts to expand its reach in the region – contained by Afghan security forces backed by US airpower and by the Taliban – security analysts warn the IS threat to Chinese interests in Pakistan will only grow over time as the group gets a foothold elsewhere in Asia and militants previously linked to al-Qaeda fold into its embrace.

“As South Asian and Southeast Asian groups have operated closely with each other, it is very likely that they will develop links,” said Rohan Gunasekera, editor of the Handbook of Terrorism in the Asia-Pacific published by London’s Imperial College Press.

Apart from Balochistan, the growing strength of IS also spells trouble for Xinjiang, where a low-intensity insurgency by Uygur Muslims has been bubbling for years. Hundreds of members of the Turkestan Islamic Party, a Uygur militant grouping, were previously based in Pakistan’s Federally Administered Tribal Areas.

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The Turkestan Islamic Party and other such foreign militant factions were targeted by Pakistani warplanes and helicopter gunships when some 170,000 Pakistan soldiers launched a conclusive counterterrorist campaign in the region in mid-2014. Many of the militants were killed and others forced to flee across the border into Afghanistan, from where most have moved to Syria to join IS and al-Qaeda affiliate al-Nusra Front.

“The Uygurs with al-Nusra and IS present an immediate, mid and long-term threat to Chinese interests,” said Gunasekera. “China should better manage the flow of Uygurs to conflict zones as they will target Chinese interests at home and abroad.”

To prevent the infiltration of Uygur and IS militants from Afghanistan into Xinjiang, China has engaged both the Afghan government and Taliban as part of unsuccessful efforts to bring about direct peace talks between the two.

To that end, Afghan Taliban representatives have twice visited China of late, late last year and again last month, for official talks. The latest delegation was reportedly led by Abbas Stanakzai, head of the Taliban’s political office in Qatar.

Unlike IS, the Taliban’s war is specific to Afghanistan and its goal is to be internationally recognised as a legitimate political force. The Taliban has “deep respect for China” and its leaders believe Beijing’s diplomatic role is key to a political settlement in Afghanistan, Rafiquddin said.

The Taliban has deployed fighters specifically to prevent the northward spread of IS and Uygur militants from Nangarhar towards Xinjiang, he said.

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Some Turkestan Islamic Party militants have taken refuge in remote eastern parts of Indonesia with the Mujahideen Indonesia Timur group, an affiliate of IS that has carried out terrorist attacks this year in Jakarta and Solo City, with the involvement of Uygur militants, according to Indonesian police officials. Uygur militants also allegedly took part in two IS attacks in Thailand last year – on the Erawan shrine and at the Sathon pier in Bangkok – that security analysts said targeted Chinese tourists.

“IS ... will continue to target Chinese interests, including in Pakistan,” said Gunasekera. “The threat posed by IS and groups associated with IS presents a very real threat to China.”

Tom Hussain is an Islamabad-based journalist and Pakistan affairs analyst