Three years ago, a little-known militant group declared a caliphate in Mosul, inspiring thousands of foreign fighters to travel to Iraq and Syria. Today, the city is back under Iraqi control, but the radical ideology of ISIS has lured even some from Singapore. What is the appeal, and what can be done to counter it?
In June 2014, some 800 militants under the command of Abu Bakr al-Baghdadi overpowered several thousand Iraqi soldiers defending their country's second-largest city and captured it.
As they swept through Mosul's abandoned streets and seized control of key buildings and mosques, they demanded that local leaders swear allegiance to their self-styled Islamic State.
When the imam of the historic al-Nuri mosque, built in the 12th century refused, he was executed.
So were several other clerics.
On July 4, al-Baghdadi donned a black robe and turban in imitation of the caliphs who ruled Iraq in the Middle Ages, mounted the mosque's pulpit, proclaimed himself "Caliph Ibrahim", and called on Muslims to join him and "do jihad".
Caliph means a steward, and the early successors to Prophet Muhammad in the seventh century were called caliphs, serving a function as both political and religious leader.
But since then, Muslims around the world have always lived under various rulers - though a few believe they should be united under one caliph, an idea Islamic State in Iraq and Syria (ISIS) has popularised.
The 43-year-old al-Baghdadi, who was one of the leaders of the insurgency against United States forces in Iraq, called for doctors, engineers and judges to help develop the militants' version of a caliphate, a message that was spread rapidly on video and across radical websites.
By then, ISIS was ruling over some eight million people, in an area the size of Jordan or Austria, and its control of oil and other resources gave it leverage in supporting its "state".
Mosul was the largest city it had captured, and followed the seizure of large parts of Syria as well as Iraq. ISIS effectively erased the border between Syria and Iraq that had been drawn - largely as a straight line - by British and French diplomats in 1916 to carve out former Ottoman lands for new colonial masters, an act that remains resented for splitting up families and tribes.
Thousands of men and women from across Asia, Europe and Africa would heed ISIS' call.
Some did not believe the reports of ISIS' reign of brutality - persecuting and killing Shi'ite Muslims, Christians, Yazidis and other minorities, many becoming refugees.
Others saw what ISIS was doing as righting historical wrongs and restoring the purity of their faith.
Some were already in Syria where a civil war had raged for some years. Among them was Haja Fakkurudeen Usman Ali, 37, who had been a manager in a Singapore supermarket.
He and his childhood friend Gul Mohamed Maracachi Maraicar, also 37, had been radicalised by the plight of Muslims in the Syrian conflict, which began in 2011.
Both were from Cuddalore in India's Tamil Nadu state, and Haja became a Singapore citizen in 2008. Gul, a systems analyst in a multinational company, was a Singapore permanent resident.
On a visit to his parents' home in India in late 2013, Haja told his family about his plans to travel to Syria.
They tried to dissuade him but his mind had been made up, his father told India's Economic Times later.
In early 2014, Haja, his wife and their three young children made their way to Syria, where they are still thought to be.
After he left Singapore, a member of the public alerted the authorities, who found out that Gul, who was still here at that time, had abetted and assisted Haja in his radicalisation and his plans to take up arms. Gul was investigated, deported and banned from entering Singapore.
Others had been radicalised around the same time, as groups like Al-Qaeda and ISIS posted videos on social media sites like YouTube to win recruits.
SOME KEY INCIDENTS
January: ISIS seizes Raqqa in Syria, makes it a stronghold
June: ISIS seizes Mosul in Iraq, declares caliphate
September: United States and Arab allies form international coalition and launch air strikes on ISIS
October: Canada's Parliament Hill attacked by gunman
March: Iraqi forces recapture Tikrit
October: Metrojet flight from Egypt to Russia bombed in mid-air
• Kurdish forces recapture Sinjar region
• Coordinated terror attacks in Paris
January: Central Jakarta attacks
March: Suicide bombers attack Brussels airport and metro
• Gunman attacks Orlando nightclub
• Iraqi forces recapture Fallujah
• Grenade attack in Puchong, Selangor
• Dhaka cafe hostage stand-off
• Truck rams into revellers in Nice on Bastille Day
October: Syrian rebels recapture Dabiq, where ISIS had promised an apocalyptic battle
December: Berlin Christmas market truck attack
• Manchester Arena bombed
• Marawi in Philippines captured by militants
June: London Bridge attack
July: Iraqi Prime Minister declares victory over ISIS in Mosul; Syrian forces close in on Raqqa
These included a 47-year-old Singaporean living in Malaysia, who went to Syria with her 37-year-old Malaysian husband, and her son and daughter from a previous marriage.
In September 2014, a group of over 120 prominent Muslim scholars wrote an open letter to ISIS stating how far its beliefs and practices had strayed from Islamic teachings and were a travesty.
It was not heeded.
Other militant groups have also distanced themselves from ISIS and its brutal tactics that include beheadings and burning captured victims alive.
Impact on Singapore Extreme material online has radicalised a number of young people from South-east Asia, including Singapore, over the past decade.
Those detected here have been counselled by religious leaders and the authorities, with a hardened few detained.
But ISIS' slick propaganda videos in various languages have upped the ante. Some time in 2013, polytechnic student Arifil Azim Putra Norja'i started seeing radical videos online.
He grew to believe that it was a religious duty for him to fight in Syria, and surfed the Internet for information on travel routes there. He also looked up how to make improvised explosive devices.
Arifil decided that if he could not join ISIS in Syria, he would try to assassinate President Tony Tan Keng Yam and Prime Minister Lee Hsien Loong. If not, he would carry out attacks in public places using weapons such as knives. He tried to persuade several others to help him carry out these plans.
A person who noticed the stark changes in him alerted the authorities, and in April 2015, Arifil was detained under the Internal Security Act (ISA) - the first self-radicalised Singaporean who harboured intent to carry out violent attacks here.
As ISIS propaganda proliferates online, the rate at which Singaporeans are being radicalised has risen.
Between 2007 and 2014, five Singaporeans were detained under the ISA and six others placed on restriction orders (ROs) that limit their activity.
But in a little over two years since then, nine Singaporeans have been detained and another six have been put on ROs for supporting ISIS and planning to join the group.
Of these 15, four had yet to turn 20. Four were in their 20s and four in their 30s. (See other story on the various ways by which the Singaporeans were radicalised.)
Some 70 radicalised foreign nationals working here have also been investigated and deported, and other travellers planning to head to Syria or with ISIS links have been turned back at checkpoints.
As a US-led global coalition marshalled forces to counter ISIS physically as well as in cyberspace, Singapore began considering being a partner to the effort.
In October 2014, PM Lee told leaders at the Asia-Europe Meeting in Milan there was "no purely military solution to this problem, because the situation in Iraq and Syria is complex".
"But it is still necessary to contain and weaken ISIS," he added, noting that any terror attack would affect not just Singapore's security but also its social cohesion, and damage racial and religious harmony.
Soon after, the Singapore Armed Forces deployed a liaison officer to the US Central Command headquarters, and an intelligence planner and Imagery Analysis Team to the Combined Joint Task Force headquarters in Kuwait.
Singapore has also supported air-to-air refuelling operations for coalition aircraft with its KC-135R tanker, joining 70 other partners in the global coalition to defeat ISIS.
But it would take nearly three years before the coalition recaptured Mosul, where residents still remain fearful of ISIS returning.
Satellite states Even as ISIS loses ground in Iraq and Syria, its affiliates have made inroads in northern Africa, Afghanistan and the southern Philippines, where militant leaders have taken an oath of loyalty to al-Baghdadi and set up wilayats, or provinces, of ISIS.
Security expert Ali Soufan, a former Federal Bureau of Investigation agent who investigated Al-Qaeda, noted this "backup plan" is akin to how after the Sept 11, 2001 attacks in the US, Al-Qaeda cultivated a network of affiliates in various parts of the world.
Foreign fighters have flocked to these regions, and returning foreign fighters - as well as others inspired by ISIS - have also launched bloody terror attacks across Europe.
With an estimated 40,000 foreign fighters having travelled to join ISIS over the past few years, international security officials are bracing themselves for a blowback should these radicalised individuals slip back into their countries.
At least 1,000 are from South-east Asia, and there have been reports that militants from other parts of the world have also travelled to the southern Philippines.
In the latest issue of its magazine Rumiyah, ISIS encourages supporters to migrate to Marawi in Mindanao if they cannot make their way to Iraq or Syria, a call that might entrench its grip in the region and see the insurgency there rage for years to come.
Singapore is also in the terror group's sights, having been flagged as a target, as have the capitals of Malaysia and Indonesia.
In 2014, extremist English-language magazine Resurgence cited the Phillips Channel - the narrowest part of the Singapore Strait - and Sembawang Naval Base in a piece on how attacks at sea could be planned.
In mid-2015, a social media post by ISIS cited Singapore as a member of the global anti-ISIS coalition that could be attacked.
And last year, the Indonesian authorities broke up a Batam cell that was talking about firing a rocket at Marina Bay Sands - and had been taking directions from Indonesian militant leaders in Syria.
The Singapore authorities also came to know of reliable information that foreign ISIS militants were considering an attack in Singapore in the first half of last year. Precautionary arrangements were made to shift and reschedule events, but the authorities have not publicly disclosed what they were.
An Arabic publication encouraging terrorists to strike Western interests also named the Singapore Exchange and a port as likely targets.
In its first Terrorism Threat Assessment Report issued last month, the Ministry of Home Affairs said the threat to Singapore remains at its highest in recent years.
ISIS' enduring appeal ISIS may be fairly new, but the ideas it pushes for have deep-seated roots that date back to the 12th century when Mongol invasions of the Middle East drove some clerics to take a hardline approach to the occupiers and regard unjust rulers as legitimate targets of attack.
Although it remains firmly a minority view, this radical world view has persisted and historians note that throughout the centuries, a vocal minority in Muslim societies have, from time to time, agitated for a return to a pristine version of their faith where a hardline interpretation of Islamic law is applied.
This minority, radical view was resuscitated by the Jemaah Islamiah, whose leader Abu Bakar Bashir, now in prison, inspired followers - including in Malaysia and Singapore - to plot attacks in the early 2000s with the goal of turning South-east Asia into a caliphate.
Leading Islamic scholars have made it clear there is no obligation for Muslims to establish an "Islamic state", let alone live in a caliphate.
Yet, followers of ISIS believe it is their duty to ensure their vision of God's law is imposed, and any government that does not do so is illegitimate and should be toppled.
The call to set up a caliphate found little support but the Soviet invasion of Afghanistan in 1979 changed things. That year, Ayatollah Khomeini's triumphant return to Iran had sparked a revolution as the country began its shift to a Shi'ite theocracy. Separately, a group of home-grown Saudi militants led by a charismatic preacher seized the Grand Mosque in Mecca. They declared a new era and called for an overthrow of the Saudi government.
The rebellion was quelled, but the authorities pledged to promote a puritan version of Islam, or Wahhabism. Occupied Afghanistan provided an outlet for young men to turn their energies to an aggressor.
Thousands of fighters would flock there, among them a young Osama bin Laden. They picked up know-how and hardline ideology that would last long after the Soviet pull-out and after the 9/11 attack in the US that killed nearly 3,000, and would lead to the US invasions of Afghanistan and Iraq.
The process set in motion a chain of terror attacks around the world, from the Bali bombings to attacks in Casablanca, Madrid, Mumbai and London, among other cities.
A series of missteps by the US in Iraq and by the country's new rulers fed an insurgency that militant groups capitalised on, and that saw ISIS emerge as the strongest - and most savage - among them.
The ongoing conflict - and reports of atrocities against civilians - fed the extremist narrative that their faith was being targeted, and that they ought to be engaged in an us-versus-them struggle to the end.
It was a narrative that many young men - and women - bought into, and continue to believe in.
ISIS has proven adept at spawning and directing attacks around the world, and has told its followers that "citizens of the countries that entered into a coalition against the Islamic State" can be killed.
In words that inspired recent attacks in Britain, France and elsewhere, ISIS spokesman Abu Musa al-Adnani outlined what dozens have tried to plan or carry out in recent months: "Smash his head with a rock, or slaughter him with a knife, or run him over with your car, or throw him down from a high place, or choke him, or poison him."
As Mr Soufan noted, even if ISIS is defeated in Syria and Iraq, its appeal persists and "it looks likely to lead a long and vicious afterlife".
Countering the threat The security authorities around the world have stepped up their guard and tried to secure their borders to detect fighters returning from, and heading to, conflict zones.
Aviation security has also been heightened. In late 2015, ISIS downed a Russian plane over Egypt's Sinai Peninsula, killing over 200 passengers.
But observers note that hardening physical security can only do so much. Key to countering the appeal of groups like ISIS is to refute and chip away at its claims to legitimacy and prevent people being swayed by its radical ideology.
In Singapore, the Religious Rehabilitation Group of scholars, who counsel terror detainees and radicalised persons, have put out material warning of the fallacy of ISIS' beliefs. The group also runs a hotline for those with queries on religious issues.
This month, a network of Islamic scholars and youth groups was set up to help counsel youth and prevent them from falling for extremism.
Singapore has been fortunate to have avoided an attack so far. But officials have also pointed out that the global situation today means it is no longer a matter of whether, but when, an attack will happen.
The biggest fear is that an attack would dent the country's racial and religious harmony. If tension and distrust between Muslims and others grows, this would play into ISIS' narrative of a world irrevocably divided between "us" and "them".
Countering such an outcome is partly why the SGSecure movement was launched last year to raise awareness of the threat.
And in recent weeks, constituencies across the island have been holding emergency preparedness days to educate residents on how to respond in an attack, and stepping up activities to build trust among people of various races and faiths.
Singapore may have to accept the risk and potential damage an attack poses to persons and property.
But just as many people in Manchester, London and other targets of recent attacks have shown, Singapore should never let an attack damage society and harmony.
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