A few weeks after the Sept 11, 2001 terror attacks on the United States, two Al-Qaeda operatives arrived separately in Singapore to start scouting for targets.
A plan was formed to detonate six truck bombs across the island.
The men, codenamed Mike and Sammy, met members of a clandestine radical network, surveilled targets and made plans to buy ammonium nitrate for the bombs.
Targets included embassies, an MRT station, water pipelines and the defence and education ministries.
Fortunately, the Government was tipped off and, by December, the first group of 13 Jemaah Islamiah (JI) members had been arrested, which averted a terror attack and its painful consequences.
By then, Mike and Sammy had left the country. Mike was actually Indonesian bomb-maker Fathur Rahman al-Ghozi, who was killed in a shootout in the Philippines in 2003. Sammy is a Canadian called Mohammed Mansour Jabarah, who is now serving a life sentence in the US.
Since the 2001 arrests, 66 individuals have been detained here under the Internal Security Act for terror-related activities.
This wave of global terrorism has posed the most significant threat to Singapore in recent decades. The threat has grown, and is unlikely to go away anytime soon in this globalised world.
Terrorism in Singapore
Today, terrorism is broadly defined as the use of violence against civilians, with the aim of intimidating people and governments,often to further a political agenda.
Cities have been key targets for terror attacks. One of the most-cited examples of terrorism is the assassination of Austro-Hungarian Archduke Franz Ferdinand and his wife in Sarajevo in 1914 by a Serbian nationalist, which sparked World War I.
After World War II, terrorists struck this region in the late 1940s and 1950s, when the Communist Party of Malaya (CPM) embarked on attacks throughout the peninsula.
Its goal was to damage infrastructure and terrify civilians while striving to create a communist state. The CPM had members as well as an underground network in Singapore, and sought to infiltrate schools, unions and political parties.
While it was part of Malaysia, Singapore was attacked by Indonesian saboteurs during Konfrontasi, a period of heavy conflict when Indonesia opposed the formation of Malaysia (see other story).
In March 1965, two saboteurs planted a bomb at MacDonald House in Orchard Road. The blast not only damaged the building, but also killed and injured people.
After Singapore gained independence, it saw its first major attack in January 1974, when four men bombed petroleum tanks on Pulau Bukom.
They hijacked a ferry, the Laju, taking five crew members hostage.
Singapore's role as a transport hub connected to the wider region has prompted terrorist groups to use it to raise funds or procure equipment for their struggles elsewhere.
In 1985, the Internal Security Department arrested and expelled key leaders of a Singapore network of the Liberation Tigers of Tamil Eelam (LTTE), which sought to create a separate state in Sri Lanka.
The network was headed by Sri Lankans working here. Another local LTTE network was disrupted in 2000.
In the 1990s, Lebanese group Hizbollah cultivated five Singaporeans, who later withdrew when asked to photograph the American and Israeli embassies.
But Hizbollah continued to conduct surveillance of the Singapore coastline, with the aim of launching attacks on vessels.
The JI network, formed in the early 1990s by radical cleric Abu Bakar Bashir, was detected only in 2001. He is now in detention at a maximum-security prison in Central Java.
For decades, he perverted Islamic teachings with the aim of setting up a caliphate in South-east Asia. Many of the Singapore JI members studied with him at the school he set up in Ulu Tiram, Johor, a 30-minute drive from the Causeway.
Several of these Singaporeans went to Afghanistan and Pakistan to train alongside seasoned militants in the early 1990s.
After the first wave of JI arrests in 2001, another 18 men were detained in subsequent months in 2002.
These arrests neutralised the Singapore JI cell, but led to disclosures that several members had fled abroad. About 10 were found and brought back in later years.
While on the run, they plotted fresh attacks. One plot targeted several embassies and the Singapore ambassador in Bangkok. Their leader, Mas Selamat Kastari, sought to hijack a plane and crash it into Changi Airport.
In Malaysia, the authorities were also clamping down on the JI network, so several of the leaders living there fled and focused their attention on Indonesia.
The JI was behind 20 bombs that went off outside churches across Indonesia on Christmas Eve in 2000, including in Batam.
On Oct 12, 2002, it launched the largest terror attack this region had seen, in Bali, where two suicide bombers detonated bombs that killed 202 people and injured dozens of others.
The attack, the largest since Sept 11, galvanised the authorities into moving against the group.
The Bali bombings - as well as follow-up attacks on the Marriott Hotel in Jakarta in 2003 and the Australian Embassy in 2004, and a second series of blasts in Bali in 2005 - served as a reminder of the ever-present threat.
They were also a reminder of the devastation and damage that a terror attack could wreak if it were to happen in Singapore.
An evolving threat
The JI in this region, like Al-Qaeda in the Middle East, has been severely weakened as a result of security initiatives.
Its appeal in Singapore has been dented by the efforts of the Religious Rehabilitation Group - Islamic scholars who counsel detainees and educate the community about the dangers of radical ideology, and who stress that the terrorists are misusing Islamic teachings for their own ends.
A group of community organisations that came together after the arrests, called the Aftercare Group, has also worked quietly with detainees and their families, helping them to reintegrate into society after their release, in a bid to ensure that the next generation does not get radicalised.
These efforts have seen 57 of those detained released to date, with only one recidivist who went back to his old ways.
But the JI has now been supplanted by newer and equally, if not more, nefarious groups. In South-east Asia, the Jemaah Ansharut Tauhid, led by Bashir, became the JI's new front.
Other militants began pursuing a more hardline path as well.
The Mujahidin in Eastern Indonesia, led by wanted militant Santoso, has been targeting soldiers and policemen in recent years for defending a regime that it deems infidel.
The Indonesian authorities have thwarted plots at home. They also discovered that some militants were setting their sights on Singapore targets.
In 2010, a map of Singapore with Orchard MRT station circled on it was recovered from a terror suspect killed by the Indonesian police during a Jakarta raid.
In 2011, the police broke up a cell led by militant Abu Umar, which wanted to target Singaporeans leaving the embassy in Jakarta.
New danger in ISIS
The threat has heightened with the ongoing conflict in Iraq and Syria, which has seen the rise of the militant group Islamic State in Iraq and Syria (ISIS).
The conflict saw the only recidivist in Singapore - self-radicalised lawyer Abdul Basheer Abdul Kader - detained again in October 2012 as he tried to travel to Syria to fight.
He was first arrested abroad in 2007 as he was about to travel to Afghanistan, and was released conditionally in 2010.
Several other individuals were counselled or given restriction orders, which limited their movements, after they were found to have been making contact with radical ideologues or militant groups abroad.
Even so, at least two Singaporeans have travelled to Syria.
A Singapore woman, whose name has not been made public, her Penang-born husband and two children from a previous marriage went to Syria in November 2013.
While the men fought, she worked as a cook, and her daughter taught English to children of foreign fighters in Syria.
A new Singapore citizen originally from India, Haja Fakkurudeen Usman Ali, joined ISIS in January last year.
He took his wife and three children with him, and recruited two college students from Tamil Nadu in India.
Observers warn that the threat is set to grow.
Last year, ISIS members from this region started a Malay-speaking unit that has been boasting on social media about its exploits.
To date, at least 500 South-east Asians are known to be fighting in Syria. A significant number have returned as well.
The fear is that just as JI members put into practice the know-how they gained in Afghanistan, a new crop of returning foreign fighters could use the skills that they picked up to plan and carry out terror attacks in the region.
Officials have warned that Singapore remains a prime - and symbolic - target. So far, it has been spared attacks like those suffered by major cities such as Sydney, Paris and London.
Thus, many wonder not just about whether an attack will hit Singapore, but also about what will happen when it does.
The reason is that the key threat posed by terrorism is not the first blast, but the aftermath: Will the social fabric hold? Will Muslims and non-Muslims be driven apart by anger and mistrust?
Speaking at an East Asia Summit symposium on terrorist rehabilitation and social reintegration this month, Prime Minister Lee Hsien Loong said Singapore had consciously sought to build trust and understanding across racial and religious lines.
"Should a terrorist attack ever occur, our society will hold together, and people will stand united," he said.
In these troubled times, even as security is stepped up, renewing and building on this trust could be Singapore's best defence against the terror threat.
Get the full story from The Straits Times.