New details about a plot to fire a rocket at Marina Bay from Batam island have raised more questions over the capabilities of the terrorist cell behind the foiled attack.
Indonesia's National Counter-terrorism Agency (BNPT) chief Suhardi Alius said the suspects planned to launch the strike from a hilltop in Taman Habibie.
The little-known nature park is located about 17km from Singapore's shoreline and just over 18km from Marina Bay Sands.
"It's true that they only did surveys and measured the angle of elevation from Habibie hill to Marina Bay, but Bahrun Naim had plans to send expert technicians to make the explosives and to prepare for the strike," he said on Monday.
Bahrun is an Indonesian militant believed to be in the Middle East fighting for the Islamic State in Iraq and Syria (ISIS).
Analysts said the bomb-makers would likely be ISIS loyalists from other militant cells, particularly from Central and West Java, which are hotbeds for militant activity.
Clear view of S'pore from park
Taman Habibie is a little-known nature park in the north-western part of Batam that overlooks the Singapore Strait at its highest point.
Locals familiar with it say that, on a clear day, they will visit the hilltop for an unobstructed view of Singapore's skyline.
Located about half an hour from central Batam, the park is relatively secluded and there are no homes or shelters along the 2km trek from the nearest road. When The Straits Times visited the park yesterday, a handful of children were playing in the area. The Marina Bay Sands integrated resort could be seen from a makeshift lookout point at the edge of the hill.
While there are no official records on how high the hill is, the summit can be accessed only by an old stairway residents call "1,000 steps", which is also the number of steps it takes to reach the top.
The park is named after former Indonesian president B.J. Habibie, who once lived nearby. Batam resident Atan said Mr Habibie used the plot of land as a helipad whenever he visited the island.
For instance, Bahrun used to live in Central Java, as did firebrand cleric Abu Bakar Bashir, while West Java was where extremist ideologue Aman Abdurrahman and the four men who mounted the Jan 14 attack in Jakarta were once based.
"Bahrun Naim is the one who turns orders from (ISIS leader Abu Bakr) al-Baghdadi into action plans in Indonesia," said terrorism analyst Mukti Ali.
The researcher from think-tank Rumah Kitab, which is involved in deradicalisation efforts in Indonesia, also noted the possible influence of Aman in such terror plots.
A key part of the plot is the rocket and whether it is capable of reaching Singapore.
"Building a rocket requires a high level of physics," Mr Kelvin Wong, an editor from military publication IHS Jane's, has said, adding there are many variables to take into account, such as wind direction, the launch angle and how much propellant to put in the rocket.
So for their purpose, the plotters would need powerful military- grade Katyusha-style, Grad or Chinese WS-1E rockets.
General Suhardi was speaking at a closed-door dialogue with editors and senior journalists from the local media in Jakarta.
Based on his revelations, the Batam cell did not seem to have either the weaponry or the expertise to launch an attack yet, said observers.
Police have arrested six members of the Batam cell since August, including its leader Gigih Rahmat Dewa, who is allegedly Bahrun's point man for the rocket attack.
The general said Bahrun had coordinated the attack using social media and it is an example of how terrorist groups such as ISIS are using social media such as Facebook and the Telegram messaging app to recruit people for their cause.
Gigih and his men are being held in Jakarta for investigations.