Two men have been detained this month under the Internal Security Act for two years, the Ministry of Home Affairs said on Friday (Aug 19).
Rosli Hamzah and Mohamed Omar Mahadi separately started tuning in to Batam-based religious radio station Radio Hang, which sometimes features speakers who preach extreme religious views.
Both also later encountered radical materials online on their own and were convinced by the Islamic State in Iraq and Syria (ISIS) propaganda.
The men wanted to travel with their family to Syria and die as a martyr.
Two others were also issued Restriction Orders, limiting their activities, for their involvement in terrorism-related activities.
Rosli, 50, a car washer, started listening to Radio Hang, which sometimes features speakers who preach extreme religious views, in 2009. In 2014, he was introduced to pro-ISIS materials through social media.
He became interested in armed jihad, and starting sharing radical material online to motivate others to support ISIS.
Rosli was "prepared to die for the ISIS cause as he thought it would bring him martyrdom status", the ministry said.
Omar, 33, a waste truck driver, started listening to Radio Hang in 2010. In 2012, he encountered radical online materials by Al-Qaeda ideologue Anwar al-Awlaki and started reading more pro-ISIS propaganda.
By 2014, he was convinced it was "his religious duty to become an ISIS fighter in Syria", the ministry said.
He read an ISIS manual and memorised a pledge of allegiance to take to ISIS leader Abu Bakr al-Baghdadi.
He was making preparations to go to Syria with his wife and two teenage children when he was detained.
Omar's wife, Dian Faezah Ismail was one of the two who were issued Restriction Orders. The 34-year-old Singaporean housewife believed the terrorist group's violent actions were legitimate and supported her husband's intentions to join ISIS.
Mohamad Reiney Noor Mohd, 26, a building technician, was also issued a Restriction Order for two years.
In his search for religious knowledge online, Reiney encountered ISIS-related materials in 2014. He became convinced by their propaganda and "aspired to fight for the ISIS 'army'", said the ministry.
But he set aside the intention to travel to Syria after "he was admonished by a close relative".
He will undergo religious counselling.
Earlier this month, Indonesian authorities arrested six militants who had been planning a rocket attack on Marina Bay from Batam. The six men were members of a little-known terror cell called Katibah GR, or Cell GR.
In April, eight Bangladeshis were given two-year detention orders under the ISA for forming and financing a pro-ISIS group.
They had been planning attacks back home in the hope of toppling the government and bringing Bangladesh under the self-declared caliphate of ISIS.
The group had a list of targets and bomb-making manuals, and was raising funds in Singapore to fund acts of terror in their homeland.
Last year, twenty-seven Bangladeshi workers who were planning terror attacks back home were arrested. All of them were deported.
The men were part of a closed religious study group that had met discreetly every week since 2013, and used the premises of a few local mosques near where some of them stayed. Most worked here for between two and seven years.
In July, Zulfikar Mohamad Shariff, 44 (above), was detained under ISA for two years for promoting terrorist group Islamic State in Iraq and Syria (ISIS) and armed jihad.
He used online platforms to propagate and spread his radical messages - which included glorifying ISIS and their violent actions and exhorting Muslims to take up arms in places like the Middle East, Palestinian territories, Myanmar and the Philippines.
At least two other Singaporeans were radicalised as a result.
In July, a 17-year-old man, who graduated from a madrasah here, was issued with an Restriction Order (RO) for two years.
He had become radicalised from accessing pro-ISIS videos, websites and social media.
The ministry said back then: "He became convinced that ISIS' violent actions were justified and harboured the intention to fight for ISIS in Syria in the future where he was prepared to die a martyr. He had sought out other like-minded individuals online, and also tried to influence his friends with his pro-ISIS views."
In April, Muhammad Fadil Abdul Hamid was detained under ISA for planning to engage in armed violence. He intended to join a terror group like ISIS and take up arms in Syria.
This is not his first brush with the law.
Fadil was released from detention in 2012 and placed on a Restriction Order, which limited his movements and activities. But he relapsed and was detained under ISA again this year.
In March, Mohamed Mohideen Mohamed Jais, 25, was issued with a Restriction Order, which limits his activities.
He had performed armed sentry duties while pursuing religious studies in Yemen.
While he did not encounter a situation where he had to open fire, he "understood that he had to return fire using the AK-47 assigned to him, with the aim to kill if there was an incursion by the Houthis".
In March, Wang Yuandongyi, 23, was placed on a Restriction Order.
He had left Singapore and was on his way to Turkey and Syria to join a Kurdish militia group that was fighting against ISIS.
On the request of the Singapore Government, he was located by the authorities of a third country he had travelled to and turned back to Singapore.
In August last year, Mohammad Razif Yahya, 27, and Amiruddin Sawir, 53, were detained under the ISA for voluntarily fighting in the sectarian conflict in Yemen.
Both had been studying in a religious institution there and had volunteered for armed sentry duties at the school.
Razif went through sniper training, and was equipped with an AK-47 assault rifle and a Dragunov sniper rifle. Amiruddin was also armed with an AK-47 rifle. Both of them were involved in fighting the rebels.