Reader Keith Heah wrote in to askST after reading the current- issues primer, "What does the terror threat mean for Singapore?"

He noticed that in the photograph accompanying the article, an officer was armed with a revolver. He said: "I would have thought that all front-line officers would be issued with more modern firearms. The officer will be at a severe disadvantage during a firefight with terrorists armed with semi-automatic or even fully automatic weapons.

Reporter Seow Bei Yi addresses his concerns.

Starting last month, the police force has been equipping front-line officers with pistols, replacing the Taurus M85 revolver that was introduced in 2002.

By 2022, all regular officers on the front line are expected to be equipped with pistols, which have greater firepower and can hold more ammunition than revolvers.

While the Taurus comes with 10 rounds, as it has a five-chambered cylinder and "speed loader" allowing a user to reload all chambers quickly at the same time, pistols generally have a larger bullet holding capacity of up to 17 rounds on a standard magazine.

Front-line officers have started to be trained and equipped with the CZ P-07 - a Central European 9mm pistol that some units in the police are using. The handgun has a capacity of 15 rounds in each magazine. Some consider this switch overdue, given the heightened security threat.

Experts have said that semi-automatic pistols are safer, with mechanisms that prevent them from going off by accident. They added that pistols can be easier to use, since with different grip methods, users will find it easier to control recoil, increase stability and improve accuracy.

But they said revolvers have been used over the years due to their reliability - with fewer moving parts, they are less likely to jam.

For patrols in public areas, servicemen from the Singapore Armed Forces have been carrying the SAR-21 rifle, which fires 450 to 650 rounds per minute.

Each serviceman typically patrols with two police officers, and soldiers are generally deployed at key installations such as Jurong Island and Changi Airport.

But last year, Defence Minister Ng Eng Hen announced that the SAF will train more units to carry out deterrence patrols in crowded areas. This is to ensure that the military can deal with orchestrated attacks - similar to those in Paris and Brussels - in hot spots such as the airport, MRT stations, shopping malls and town centres.