The army and security agencies have tightened surveillance and counter-terrorism operations against the Islamic State (IS), amid reports the extremist group is attempting to spread to Southeast Asia.
The alert comes after Malaysian police reported that they had arrested five suspected IS militants including an Indonesian man in the state of Selangor and in the southern state of Johor last week.
Two of the militants were allegedly plotting attacks in the Klang Valley, just outside Kuala Lumpur where the Asean Summit is being held this week.
"We have followed IS movements and are on alert after several arrests were made in Malaysia," a security source said.
The army, police, and security officers are working with their counterparts in Malaysia, the Philippines and Indonesia. Jakarta has also traced links between Jemaah Islamiya and IS extremists.
That has triggered concerns there might be similar links between southern militants and the IS.
Gen Aksra Kerdphol, head of the peace dialogue with the southern militants, and some leading academics have dismissed the connection, however, saying there are no irregular activities involving terrorists in the restive South.
Saravuth Aree, of Chulalongkorn University's Islam Studies, and Panitan Wattanayagorn, adviser to Deputy Prime Minister and Defence Minister Prawit Wongsuwon, said southern insurgents have different ideologies from the IS, and are unlikely to join the extremist movement.
"Southern insurgents have their own identity and their target is limited to an area with historical importance," said Mr Panitan, adding secession is the goal of the southern insurgents, not indiscriminate violence like the IS.
However, security officers said it's better to apply the "better safe than sorry" rule when dealing with the issue.
At least they are sympathetic to Muslims' grievances and anti-US sentiment.
Their concerns stem from reports that youngsters from various countries are being lured into joining the IS against the US and its allies.
In particular, there are reports that two Thai students who studied in Indonesia left the country for Syria late last year and have not returned.
Intelligence officers have followed the case closely and are trying to track them down.
Moreover, they found some young Muslims in the South who sympathise with insurgents have used social media to express their support for the southern insurgency and the IS, using the Arab or Malay languages.
This suggests the group's anarchic messages are starting to gain traction with the young, even if little hard evidence has emerged of Thais joining the movement in the Middle East.
Cyber warfare and security command officers say the IS has succeeded in using the internet in recruiting young people to join the radical movement.
They said some Thai students in Bandung, Indonesia, have expressed support for the IS and this may reflect the thoughts of young Muslims in the South.
This makes it necessary for intelligence officers to escalate surveillance in the area, as they cannot afford to take security for granted.
In addition, security officers are paying attention to possible links between ethnic Uighurs and the IS given a warning issued by China that some Muslim minorities have joined hands with the radical force.
As in the case of the Erawan shrine bombing last August, Thailand has to prepare for the Uighur factor that may pose a threat to national security.
Although Prime Minister Prayut Chan-o-cha has attempted to ease concerns over terrorism fears, saying Thailand is not a party to conflicts and there is no need to panic, he does admit that risks do exist because terrorism knows no boundaries.
"Everyone must help keep a lookout, not just pray for safety. We cannot find a place that is 100% safe in this world; we have to help look out for one another," said the prime minister.
Wassana Nanuam is a senior news reporter covering military affairs for the Bangkok Post.