Four Singaporeans have been arrested under the Internal Security Act for engaging or intending to take part in violence abroad.
The Ministry of Home Affairs said yesterday that Mohammad Razif Yahya, 27, and Amiruddin Sawir, 53, were detained in August last year for voluntarily fighting in Yemen's armed sectarian conflict while at a religious institution there.
Mohamed Mohideen Mohamed Jais, 25, had also done armed sentry duties there and was issued with a Restriction Order (RO), which limits his activities, this month.
Unlike previous announcements of terror-related arrests, none of the four picked up was planning to join the terrorist group Islamic State in Iraq and Syria (ISIS).
But in the first known case of its kind, Wang Yuandongyi, 23, was planning to join a Kurdish militia fighting against ISIS.
He left Singapore in January this year for a third country, and intended to make his way to Turkey and Syria.
He took along Singapore Armed Forces-issued military gear like his uniform and boots.
The ministry said investigations showed that Wang began to empathise with the plight of the Kurds in Syria and started detesting ISIS late last year.
He was also looking to escape from setbacks, such as a failed business venture.
In December, he got in touch with a Kurdish militia group online and discussed possible travel routes. His plans were thwarted when someone reported him to the authorities.
At Singapore's request, he was located by the authorities of the third country and returned to Singapore. Wang was placed on a RO this month.
"The Government takes a stern view against anyone who supports, promotes, undertakes or makes preparations to undertake armed violence, regardless of how they rationalise such violence ideologically, or where the violence takes place," the ministry said.
It noted that though Wang was not driven by ideology to fight abroad, the fact remains that he intended to engage in an armed conflict overseas.
"Geography does not mask the fact that such individuals would have demonstrated a dangerous tendency to support the use of violence," the ministry added.
"Their involvement in overseas conflicts can also jeopardise Singapore's national interests, including our bilateral relations. They are deemed to pose a threat to Singapore's security, and will be firmly dealt with in accordance with our laws."
The ministry noted that Razif had begun studying in a religious institution in Yemen in January 2010, and Amiruddin went there in July 2013.
The two signed up for armed sentry duties against possible attacks by Houthi rebels, who are Shi'ites.
Razif went through sniper training, and was armed with an AK-47 assault rifle and a Dragunov sniper rifle. Amiruddin was equipped with an AK-47 rifle. Both were involved in fighting the Houthis.
"Razif and Amiruddin were prepared to kill and be killed as 'martyrs' in the sectarian conflict in Yemen," the ministry said.
"They have demonstrated a readiness to use violence to pursue their religious cause. As such, they are assessed to pose a security threat to Singapore," it added.
As for Mohideen, he did armed sentry duties while studying in Yemen from 2009 to early 2011.
While he did not use his arms, 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".
Security analyst Susan Sim said the Government's stand was clear. "Once a person gets used to the idea of killing to achieve objectives he has decided for himself - what's to stop him from doing the same thing in Singapore?"
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