Indonesia has been hit by a spate of ISIS-inspired attacks mounted by different domestic militant groups since the start of the year.
But the worrying trend is of more lone-wolf terrorists striking random targets in the name of the Islamic State in Iraq and Syria (ISIS) militant group, said police chief Tito Karnavian.
Speaking to reporters after a meeting at the Presidential Palace yesterday, General Tito said that while the "old network" of terrorist groups remains the larger threat, "lone wolf" cases are on the rise.
"They are being recruited through social media and trained online, including being taught how to make bombs... and then they go on their missions alone," he added.
The four-star police general did not give details of the lone-wolf cases he was referring to, but there were at least three such incidents in recent months.
One of them took place last Thursday, when an unemployed 21-year-old man attacked two officers at a police post in Tangerang, about an hour's drive from Jakarta, with knives and pipe bombs.
The suspect was shot by a third police officer and died en route to hospital. ISIS has claimed responsibility for the attack.
The Tangerang case came after two suicide bombers separately tried to launch an attack on a police outpost in Solo and a Catholic church in Medan in July and August respectively. Both were unsuccessful because in one case, the bombs failed to detonate, and in the other, the militant was stopped by police.
According to Gen Tito, militant groups make use of both "lone-wolf and wolf-pack patterns", with the former harder for the authorities to detect. "It's simpler to do it alone, like in Medan," he said.
Security analysts have long warned about the rising threat of lone-wolf militants, describing them as more dangerous because they are harder to track.
The frequency of such attacks in the region and around the world has increased, with more people becoming self-radicalised.
It all started when ISIS leader Abu Bakr al-Baghdadi rallied supporters in November 2014 to carry out lone-wolf attacks wherever possible. "Oh soldiers of the Islamic State, erupt volcanoes of jihad everywhere. Light the earth with fire against all dictators," he had declared.
The West has been similarly hit by lone-wolf terrorists who acted on their own but believed they were answering the call of ISIS.
Many of them were radicalised and learnt how to attack their targets using social media and smartphone messaging apps.
That is why Indonesia's National Counter-Terrorism Agency (BNPT) recently set up a special team tasked with countering any radical campaigns online, but that in itself has been a challenge.
"We can block Internet websites but not social media," said BNPT chief Suhardi Alius yesterday.
He said social media plays a big part in the rising number of lone-wolf terrorists around the world because people are "inspired by what they pick up" online.
"This is not only an Indonesian problem, but it is also the same elsewhere in France and Germany," said General Suhardi.
The latest figures indicate that there are 139 million Internet users in Indonesia and Gen Suhardi wants to build greater awareness of radical ideas online among users.
"We also have to cooperate across different countries," he added. "This is because Indonesia is not the only target."