Six suspects were arrested in an alleged plot to launch a rocket attack on Singapore's Marina Bay from the Indonesian island of Batam, Indonesian media reported Friday.
Singapore's Minister of Defence Ng Eng Hen confirmed in a Facebook post late Friday that one of the alleged plans of the group of suspects was to use rockets to attack targets in Marina Bay from Batam.
"We should assume that there may be more plots, other terror cells on the lookout for ways, and new munitions to penetrate our defenses," Ng said.
Parts of the Batam Island are as little as 20 kilometers away from Singapore, although it wasn't immediately clear where the attackers were based.
Singapore's Marina Bay area is home to both office towers and one of the city-state's casino-resorts, complete with three hotel towers, a convention center, shopping mall, science museum and casino.
Singapore's Ministry of Home Affairs (MHA) said in a statement that it was aware of the suspects' plot and that the city-state's security agencies had coordinated closely with Indonesian authorities since the plan's discovery to monitor the group's activities.
"In response to this threat and the prevailing security situation, police and other agencies have been stepping up inland and border security measures," the MHA statement said.
The six suspects, aged 19 to 46, were arrested on Friday by Indonesia's elite counter-terrorism squad, Singapore's Today newspaper reported, noting that all but one worked at a fabric factory. The sixth suspect was reportedly a bank executive, Today reported.
Singapore's government declined to release additional details about the alleged plot, including how credible it was considered.
It wasn't clear whether the suspects would have had access to materials for a rocket attack.
Greg Waldron, the Asia managing editor at Flight Global magazine, said that based on media reports, the alleged plot sounded "a bit half-baked."
"If they had access to military-grade weapons, that would be an alarming development. If it's a plot using homemade (weaponry), it would be extremely difficult to develop a system like that," said Waldron, who is based in Singapore.
He noted that a homemade system would need propellant and a guidance system and added that if the suspects built it on their own, they likely wouldn't be able to test it.
"For an amateur doing something on their own, it would be quite a feat. They're more likely to blow themselves up than to get it over here," he said.
Other attempts to launch larger-scale terrorist attacks on Singapore have been similarly planned.
Mas Selamat Kastari, an Indonesian-born Singaporean, was detained in Singapore in early 2002 on suspicion of plotting to bomb the city-state's Changi Airport, potentially by crashing a plane.
In an incident that became an international embarrassment to Singapore, he escaped detention in 2008 by climbing out of a bathroom window. Mas Selamat, who had a distinct limp after falling out a window during a previous escape attempt, wasn't recaptured until more than a year later in Malaysia. He was reportedly plotting additional terror attacks while a fugitive.