ALL terrorist attacks are sickening, but some more so than others. On May 13th a family of suicide bombers killed 13 people and wounded more than 40 others in attacks on Christian churches in the city of Surabaya in eastern Java. The father drove a car packed with explosives into one Sunday service. His two sons, aged 16 and 18, struck a second. The mother and two daughters, aged just 9 and 12, blew themselves up at a third. It was Indonesia’s deadliest terrorist attack since 2005 and the first to involve women or child bombers.

Later that day another family apparently plotting a similar attack accidentally killed themselves at their home near Surabaya. The next day a third family wounded 10 people when they blew themselves up at the gates of Surabaya’s police headquarters. The father, mother and two sons were killed but an eight-year-old daughter survived. CCTV images showed her stumbling around after the blasts. And on May 16th an assailant ran over a policeman in Sumatra. Four sword-wielding accomplices were shot dead.

Joko Widodo, Indonesia’s president, condemned the attacks as barbaric. They have heightened fears of a resurgence of Islamist terrorism in Indonesia. Police say the father involved in the Surabaya church bombings was the local head of Jemaah Ansharut Daulah, or JAD, a loosely organised militant network that supports Islamic State. He led a religious study group attended by all three families where he showed gruesome jihadi videos. IS claimed to be behind the attacks, although contrary to initial reports, none of the bombers had trained with it in Syria.

The authorities are now racing to reassure the world that the country is safe ahead of the Asian Games in August in the cities of Jakarta and Palembang, and the annual meetings of the IMF and World Bank in October on the island of Bali. The bombings came less than a week after Islamist militants at a high-security prison outside Jakarta killed five guards during a 36-hour uprising, for which IS also claimed responsibility. Police have arrested or killed at least 20 suspected JAD terrorists in an ongoing sweep.

Sidney Jones of the Institute for Policy Analysis of Conflict, a think-tank in Jakarta, says that the Surabaya attacks underline the need for improved surveillance. She describes existing programmes to rehabilitate IS sympathisers, including some 500 Indonesians Turkey has sent home on suspicion of seeking to cross into IS-controlled parts of Syria, as “rudimentary”. Analysts warn that returnees could bring back more deadly methods of terror.

That would be a reversal after Indonesia’s success in crushing the network responsible for a horrific bombing in Bali in 2002, in which 202 people were killed. Recent attacks have appeared amateurish by comparison, although the latest ones attest to a degree of co-ordination and planning not seen for more than a decade. The home-made explosives used in them were also more powerful than those used in other recent bombings.

Jokowi, as the president is universally known, has pledged to strengthen the country’s terrorism laws by decree if parliament does not do so by June. Revisions were proposed shortly after a terrorist attack in Jakarta in 2016 but have languished in the legislature ever since. Critics say the vaguely worded revisions, including ones that could allow a larger counter-terrorism role for the military, would be counterproductive. Ms Jones says efforts to prevent terrorism need to target areas where militants are known to be active, and aimed at women and teenagers as well as men: “The danger is that, after the initial shock, the public slips back into believing that the problem is over,” she says.