"Terrorists" in speedboats, suspected of smuggling arms, were intercepted in Singapore waters off Changi Coast Road, but not before one of them "escaped" to the eastern coast.
But he was swiftly arrested, along with an accomplice, by officers from the Coastal Hardening Strike Force outside the National Service Resort and Country Club, who arrived on the scene in police cars with sirens blaring.
The land demonstration was a first for Exercise Highcrest, a multi-agency biennial maritime security exercise coordinated by the Singapore Maritime Crisis Centre, held from last Thursday to yesterday.
Senior Minister of State for Defence and Foreign Affairs Maliki Osman yesterday observed this scenario play out, one of a number to test the readiness of multiple agencies to respond to such threats.
He said: "We saw what happened in Mumbai, even though it was almost 10 years ago in 2008. We have learnt from those experiences... and developed our own responses to a terror incident coming from sea."
The sea portion involved a Republic of Singapore Navy (RSN) Littoral Mission Vessel, two Police Coast Guard high-speed interceptors and a patrol interdiction boat. Warning flares were fired by one of the interceptors and the patrol interdiction boat, before the terrorist boats were surrounded by the vessels.
This year, Exercise Highcrest involved about 300 personnel from 14 government agencies, including the RSN, Singapore Police Force, Singapore Civil Defence Force, Singapore Customs, Immigration and Checkpoints Authority, and the Maritime and Port Authority of Singapore.
Number of personnel involved in Exercise Highcrest.
Number of government agencies involved in the exercise.
Number of days the exercise was on, during which a range of maritime terrorism scenarios was tested.
A range of maritime terrorism scenarios was tested during the eight-day exercise, including the sea infiltration and a chemical attack on board a ferry.
Previous Highcrest exercises included the storming of a hijacked merchant vessel and rescuing hostages on a passenger coach at Tanah Merah Ferry Terminal.
This year's exercise took place in between two Exercise Northstar counter-terrorism drills.
The first on Tuesday last week involved a simulated attack where gunmen shot people at the Changi Airport MRT station and a suicide bomber blew himself up in Changi Airport Terminal 3. Phase 2 of Northstar will happen tomorrow at the Home Team Tactical Centre.
Colonel Nicholas Lim, who is the director of the National Maritime Sense-making Group - the intelligence arm of the Singapore Maritime Crisis Centre - said that it is the first time that Highcrest is working with Exercise Northstar. It was carried out this way to see how scenarios that happen on land could impact sea operations, and vice versa.
"It's important that we actually have a presence in the maritime domain, with it being porous and easily accessible, so that we're able to stop people from leaving (if there's an attack that happens on land)," he said.
Asked whether more integrated exercises could be expected, Dr Maliki said: "The whole-of-government approach towards preparing for security challenges is critical and important. Moving forward, we'll see a lot more of such integration."
Singapore's maritime environment also poses unique challenges as it is among the busiest in the world with over a thousand vessel movements every day, said Senior Lieutenant-Colonel Ang Jeng Kai, operations group commander of the Maritime Security Task Force, who was involved in Exercise Highcrest.
"Many of (the vessels) are small craft that traverse across our waters so it is not easy to identify a threat," he said.