A joint exercise was conducted by the Republic of Singapore Navy (RSN) and the Singapore Police Force (SPF) on the island of Pedra Branca last month, the RSN has revealed on its Facebook page.
As part of the exercise, a scenario involving an armed civilian intruder was simulated, with the RSN and police intercepting and taking down the threat, the navy said yesterday.
"The RSN and the SPF conduct regular exercises to ensure that our contingency plans for the defence of Pedra Branca against any threats or intrusions are well practised," the Facebook post read.
The exercise was held following "months of planning and preparation", the navy said, adding that a round-the-clock watch over the island is maintained to guard against intrusions.
The waters off Pedra Branca were the site of a fatal collision between an oil tanker and a United States warship on Aug 21. Ten American sailors from the USS John S. McCain died in the incident.
Pedra Branca has also been the source of a territorial dispute between Singapore and Malaysia.
The International Court of Justice (ICJ) had, in a 2008 judgment, awarded sovereignty over Pedra Branca to Singapore and neighbouring Middle Rocks to Malaysia.
But in June this year, Malaysia filed an application at the ICJ to declare that the waters around Pedra Branca were within its territorial waters.
Singapore has said that it will oppose the bid, which it called unnecessary and without merit.
Last month, a Malaysian navy ship berthed for the first time at the new Abu Bakar maritime base in Middle Rocks.
Malaysia's navy chief, Admiral Ahmad Kamarulzaman Ahmad Badaruddin, said last month that the fast-attack craft, KD Perdana, was not being permanently positioned in Middle Rocks.
However, the vessel would still frequent the base and carry out patrols in the area with other vessels to ensure maritime security, the admiral had said.