Another two maids who were radicalised have been detected here in recent months, bringing the total number of such cases since 2015 to nine.
The two new cases were revealed in Parliament yesterday by Second Minister for Home Affairs Desmond Lee in response to Mr Christopher De Souza (Holland-Bukit Timah GRC), who asked for an update on the threat posed by radicalised foreigners in Singapore.
Mr Lee said the pair came from different parts of Indonesia.
One of them was a 25-year-old who worked in Singapore for two years - the youngest among the nine radicalised maids detected so far. She had intended to travel to Syria with her foreign boyfriend to join the Islamic State in Iraq and Syria (ISIS).
The other, aged 28, worked in Singapore for close to five years.
"Similar to the earlier cases, both of them were ISIS supporters, radicalised through social media," said Mr Lee. All nine foreigners have since been repatriated to their home countries.
None had plans to carry out acts of violence here. Mr Lee said the two maids are not known to have influenced their friends here.
He added that the Ministry of Home Affairs (MHA) has worked closely with the Ministry of Manpower (MOM) to address the threat of radicalised foreign workers.
This is done through an advisory for foreign workers here to be alert to signs of radicalisation. This advisory was prepared after the arrest of radicalised Bangladeshis last year, he said.
Besides a settling-in programme to sensitise maids to the threat of radicalisation, foreign workers will be regularly engaged by agencies such as MOM, the Islamic Religious Council of Singapore (Muis) and the Religious Rehabilitation Group.
"We will do more to sensitise our foreign workers to Singapore's multi-religious social values," said Mr Lee.
Terrorism emerged as one of the major issues discussed during question time in Parliament yesterday, with many MPs noting with concern recent attacks in Britain and the Philippines.
Mr Ang Wei Neng (Jurong GRC) and Mr Zaqy Mohamad (Chua Chu Kang GRC) asked if there are new initiatives to counter copycats of lone-wolf attacks, in the light of recent terror incidents abroad.
Mr Lee said that together with other agencies, MHA is reviewing existing security measures in public spaces, in particular against hostile vehicle attacks.
"Possible new measures include putting up bollards or security barriers," he said. However, such measures must strike a balance between enhancing security and disrupting daily activities through restrictions.
An Infrastructure Protection Act will be introduced this year too, to help protect critical infrastructure and large-scale developments.
Replying to Ms Cheng Li Hui (Tampines GRC), who asked about minimising the risk of self-radicalisation among students and school staff, Mr Lee said the authorities inform the Ministry of Education (MOE) of the overall security threat climate and risks. "Based on this, MOE works with us and reviews and calibrates the security measures for schools," he said.
Schools are key platforms to counter dangerous influences, he added, as youth spend a significant proportion of time in educational institutions, and consume a lot of information from the Internet.
"Radical preachers and terrorist groups know this. They exploit these media to spread their radical ideologies and terrorist propaganda," he added.
"Most of the Singaporeans who have been radicalised were younger than 30. Some were in their teens," said Mr Lee. "They were mainly self-radicalised online."
This is why, besides incorporating counter-terror messages in the secondary school curriculum, schools provide a supportive environment for strong, positive relationships.
Staff also look out for students who display anti-social behaviour, he said.
But Mr Lee added: "Family members, friends, colleagues, religious leaders and community leaders also play an important role."