Indonesia must strengthen its defenses against Islamic State and work with neighboring countries to fight it, Jakarta's police chief said on Friday, a day after an attack by suicide bombers and gunmen in the heart of the Southeast Asian nation's capital.
Just seven people were killed in the three-hour siege near a busy shopping district despite multiple blasts and a gunfight, and five of them were the attackers themselves.
Nevertheless, it was the first time the radical group has targeted the world's most populous Muslim nation, and the brazenness of the attack suggested a new brand of militancy in a country where low-level strikes on police are common.
Police chiefs across the country were put on high alert, some embassies in Jakarta were closed for the day and security was stepped up on the resort island of Bali, a draw for tourists from Australia and other Asian countries.
Media reported that three people suspected of plotting an attack were arrested before dawn in Depok, just south of Jakarta. Metro TV said there was no indication that the men - which it described as a bomb-maker, a firearms expert and a preacher - were linked to Thursday's attack.
Police declined to confirm the arrests.
"We need to pay very serious attention to the rise of ISIS," Jakarta police chief Tito Karnavian told reporters outside the city's oldest department store, Sarinah, where the attack unfolded on Thursday.
"We need to strengthen our response and preventive measures, including legislation to prevent them ... and we hope our counterparts in other countries can work together because it is not home-grown terrorism, it is part of the ISIS network," he said, using a common acronym for the Syria-based group.
Luhut Pandjaitan, Indonesia's chief security minister, told reporters his office was working with parliament to make changes to legislation that would allow preemptive arrests.
Experts agree that there is a growing threat from radicalized Muslims inspired by Islamic State, some of whom may have fought with the group in Syria. However, they said the low death toll on Thursday pointed to the involvement of poorly trained local militants whose weapons were crude.
An Indonesian and a man of dual Canadian-Algerian nationality were killed. Twenty-four people were seriously wounded, including an Austrian, a German and a Dutchman.
Islamic State said in its claim of responsibility that "a group of soldiers of the caliphate in Indonesia targeted a gathering from the crusader alliance that fights the Islamic State in Jakarta".
Karnavian confirmed that Islamic State was responsible and named an Indonesian militant, Bahrun Naim, as the mastermind.
Police believe Naim leads a militant network known as Katibah Nusantara and is pulling strings from Raqqa, Islamic State's de facto capital in Syria.
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"His vision is to unite all ISIS supporting elements in Southeast Asia, including Indonesia, Malaysia and the Philippines," Karnavian said.
Islamist militants from those three countries have a record of working together and several Malaysians are known to have carried out suicide attacks in the Middle East.
Echoes of Paris
Indonesia has seen attacks by Islamist militants before, but a coordinated assault by a team of suicide bombers and gunmen is unprecedented and has echoes of the sieges seen in Mumbai seven years ago and in Paris last November.
In a recent blog post, entitled "Lessons from the Paris Attacks", Naim had urged his Indonesian audience to study the planning, targeting, timing, coordination, security and courage of the jihadis in the French capital.
Australian Attorney-General George Brandis, who was in Jakarta recently to bolster security coordination, told the Australian newspaper he had "no doubt" Islamic State was seeking to establish a "distant caliphate" in Indonesia.
The country had been on edge for weeks over the threat posed by Islamist militants, and counter-terrorism police had rounded up about 20 people with suspected links to Islamic State.
There was a spate of militant attacks in Indonesia in the 2000s, the deadliest of which was a nightclub bombing on Bali that killed 202 people, most of them tourists.
Police have been largely successful in destroying domestic militant cells since then, but officials have more recently been worrying about a resurgence inspired by Islamic State.
The head of Indonesia's second-largest Muslim organization, Din Syamsuddin, warned on Friday against "Islamophobia" following the Jakarta attack but also urged Muslims not to be influenced by "radical teachings".
Still, many experts believe that Indonesia, a vibrant democracy where the vast majority of Muslims practise a moderate form of Islam, is most unlikely to be tipped into a cauldron of Islamist militancy.
"It is true that a tiny number of the country’s army of poorly educated, desperately underemployed young men are attracted to the guts-and-glory narrative spun by ISIS," author and long-time Indonesia foreign correspondent Elizabeth Pisani wrote in the Financial Times.
"But their discontent is based on economic rather than religious or political marginalization," she said.