The National Police say they are maintaining utmost vigilance regarding the threat from local groups affiliated with the Islamic State (IS) movement after the recent arrest of nine suspected terrorists in several regions.
"We will resume the highest level of alert, because it is not only the public that is under threat, but also senior police officials," National Police spokesman Insp. Gen Anton Charliyan told journalists at the force's headquarters in Jakarta.
Anton said that the main targets of the terror groups were churches and police stations, with targets spread across Sumatra, Java and Kalimantan.
However, he declined to identify any of the targets.
"The groups may also look to attack other radical groups that are challenging IS," he added.
According to Anton, Syria-based leaders of IS have mandated attacks by smaller affiliated groups in Indonesia.
He declined to say if members of the groups in question were understood to have been trained by IS in Syria.
"We're still investigation the matter," he said.
Previously, the National Police arrested nine terrorist suspects during a two-day operation beginning on Friday.
The nine were arrested in separate locations, namely Tasikmalaya in West Java, Cilacap and Sukoharjo in Central Java and Mojokerto and Gresik in East Java.
The National Police's counterterrorism unit, Densus 88, launched the operation in Cilacap with the arrests of two suspects, RS and YS, Anton explained.
Later the same day, two further suspects, Z and AA, were arrested in Tasikmalaya.
On Saturday, officers detained a suspect identified as AB in Sukoharjo, as well as four suspects, M, K, TP and IR, in Mojokerto.
The police believe that the nine suspects belong to a terrorist group based in Klaten, Central Java.
In the course of the arrests, officers seized evidence including fertilizer, a map of Jakarta, CO2 for an airsoft gun, a machete and a light.
Anton encouraged people to be alert and careful during the celebrations of Christmas and New Year.
Separately, Cabinet Secretary Pramono Anung said National Police chief Badrodin Haiti had informed the President of potential disturbances ahead of the year-end holiday period.
The President, Pramono added, had in turn asked the police to remain alert.
"We will beef up security and the police will increase the number of personnel. In addition to the [security] measures enacted by the police and the Indonesian Military [TNI], the government also hopes for public participation [in ensuring a peaceful year-end holiday]," Pramono said.
He reiterated the stance of the government on radicalism, stressing that a soft approach was essential to addressing the root causes of the problem and that taking a hard line could prove countereffective.
In total, an estimated 514 Indonesians have gone to Syria and Iraq to fight with IS, with around half of them Indonesian citizens who were already residing in nearby countries as students or migrant workers prior to the rapid rise of the militant group.
Indonesia ranks 31st in the Institute for Economics and Peace's 2014 Global Terrorism Index from 162 countries surveyed for terrorism impact, scoring 4.67 on a scale of 1 to 10.