Indonesian police have stepped up patrols in public areas where westerners gather in Indonesia after the arrest over the weekend of four suspected foreign Islamic State-aligned radicals.
The men were arrested on Saturday with three Indonesian nationals heading towards an established hide-out in Poso, Central Sulawesi, where wanted terrorist Abu Wardah Santoso has long operated.
Indonesian police spokesman Agus Rianto said the men had travelled on Turkish passports, but, when police tried to interview them in Turkish, they did not speak the language. It's believed they are Uighurs, from a muslim minority group in western China.
Police have not yet managed to conduct an interview.
Mr Agus said security had not yet been stepped up at embassies and international schools, but that police had increased patrols.
Former Jemaah Islamiyah terrorist and now deradicalisation expert Nasir Abbas, said that Santoso, who had already pledged allegiance to the Islamic State, was "very important" for jihadist groups in Indonesia.
"For the groups who still want to carry arms and carry out operations, he's the one who still exists," Mr Nasir said.
Santoso has hidden out for years in the jungles of Central Sulawesi, and runs a group called Eastern Indonesia Mujahideen.
Mr Nasir said the four-man delegation who attempted to reach him was probably trying to re-establish global jihadist links between Santoso and the Islamic State of Iraq and the Levant, ISIL, also known as ISIS and Islamic State.
Mr Nasir said that, when he was training in Afghanistan in the early 1990s, there were a number of Uighur fighters there. Earlier this month, a Chinese fighter was captured in Iraq apparently fighting for ISIS.
Terror expert Sidney Jones said that foreign jihadis on Indonesian soil "substantially ups the ante" for Indonesia.
Australia's announcement over the weekend that it will join the US-led coalition to fight ISIL has led to speculation that Indonesian jihadists could turn again to the "far enemy" and target western interests in Indonesia.
However, Mr Nasir said it was unlikely that ISIL would launch such attacks without a specific instruction from Abu Bakr Baghdadi, the group's leader.
"It depends on what Abu Bakr Baghdadi orders, because the radicals believe he's ordered a caliphate, and they won't do any operations outside Syria and Iraq unless they get a statement or order from him," Mr Nasir said.
Al Qaeda's links with radical Indonesian group Jemaah Islamiyah in the 2000s, and Osama Bin Laden's orders to take revenge on the United States and its allies, prompted two Bali bombings, the Australian embassy bombing and other attacks against western interests in Indonesia in which 92 Australians died.
President Susilo Bambang Yudhoyono convened a special limited meeting on Sunday of his security cabinet, and warned again that Indonesia needed to be vigilant about the new group.
"We should not let our guard down and thing the danger is only overseas … such violence could happen here," Dr Yudhoyono said.
