Besides helping to make bombs used in the Jan 14 terrorist attack in Jakarta, Dodi Suridi also put together an improvised rocket launcher.

The militant had apparently learnt how from a video on YouTube and made the device using a plastic tube filled with potassium nitrate from fertiliser, among other substances.

How he assembled the improvised explosive devicewas revealed in the prosecution's submissions at his sentencing yesterday. Dodi, who once worked as a traditional healer, was said to have successfully test-fired the makeshift rocket launcher at a rice field in an undisclosed location.

The 23-year-old is from Cirebon, a city in West Java, where he first pledged his allegiance to the Islamic State in Iraq and Syria (ISIS).

There was no mention of who had directed him to build the rocket launcher or if other militants had a target planned for the weapon.

Revelations that Dodi was able to build and test-fire an improvised rocket launcher came two months after Indonesian police foiled a terrorist plot to fire a rocket at Marina Bay in Singapore from Batam island.

In August, the police arrested six members of a domestic militant cell in Batam linked to the plot, including its leader Gigih Rahmat Dewa.

Analysts, however, said the cell did not appear to have the expertise or weaponry to launch such an attack from about 17km away. They added that successfully striking Singapore from Batam would require military- grade rocket launchers.

Francis Chan