A "terrorist" speedboat on its way towards Singapore from the east coast was swiftly intercepted by a Police Coast Guard vessel after the authorities had received intelligence of suspicious activity.
As part of the heightened security level, a Singapore navy littoral mission vessel, RSS Independence, moved in to divert maritime traffic and secure the area.
Immigration and Checkpoints Authority officers conducted enhanced security checks at the nearby Tanah Merah Ferry Terminal, while the Maritime and Port Authority worked with ferry operators to reschedule ferry movements and inform travellers of the change in plans.
This two-hour demonstration on land and at sea yesterday was part of the biennial Exercise Highcrest meant to test the national agencies' coordinated response to maritime security threats.
It was the first time commercial partners - ferry operators and the Singapore Cruise Centre, which manages Tanah Merah Ferry Terminal - were involved in the exercise.
There were more than 200 participants in the exercise, which began on Oct 16 and ends today.
Senior Minister of State for Defence Heng Chee How and Senior Minister of State for Transport Lam Pin Min witnessed the exercise yesterday, along with the Chief of Navy, Rear-Admiral Lew Chuen Hong.
Mr Heng said that with heavy traffic in Singapore's waters, some of the ships can turn rogue and attack Singapore targets.
We know it's going to cause inconvenience to not only just the passengers, but also to the public as well as the operators. Therefore it's very important to work closely with our commercial partners, so that in the event that there's a heightened security alert, we'll be able to... minimise inconvenience caused to travellers.
SENIOR MINISTER OF STATE FOR TRANSPORT LAM PIN MIN, on maritime security in Singapore's waters.
"(In such a case), how do we then be pre-emptive about it and be very coordinated, to be very exercised, so that our reflexes are very finely honed," he told reporters.
Dr Lam said maritime security was of utmost importance, with almost seven million passengers passing through Singapore's ferry terminals every year.
"We know it's going to cause inconvenience to not only just the passengers, but also to the public as well as the operators.
"Therefore, it's very important to work closely with our commercial partners, so that in the event that there's a heightened security alert, we'll be able to... minimise inconvenience caused to travellers," he added.
At the ferry terminal, forward screening was demonstrated as part of the enhanced security checks.
This initiative, implemented since Aug 19 this year, is meant to detect threats early, such as adversaries armed with explosives and firearms, before they enter the arrival passenger hall.
A handheld trace detector, the Sabre 5000, was used. It can detect trace amounts of explosives, chemical-warfare agents, and drugs in seconds.
Exercise Highcrest, which was first held in 2013, is coordinated by the Singapore Maritime Crisis Centre based in RSS Singapura-Changi Naval Base.
The other agencies involved in this year's exercise are the Singapore Civil Defence Force, the police and the Singapore Customs.
Over the period of the exercise, the agencies planned how to tackle a variety of scenarios, such as terrorist infiltration by the sea, attacks by small boats, and ferry hijacks.