To describe Friday’s horrific gun and bomb assault on a Sufi mosque in the northern Sinai peninsula as the deadliest attack by armed militants (rather than the state) in Egypt’s modern history understates it. It is one of the worst to happen anywhere in recent years. Officials say more than 300 worshippers, including 27 children, were killed. As in Manchester, Paris or Barcelona, families are devastated and a wider community left fearful – as its perpetrators desired.

It is also unprecedented, despite the area’s troubled and bloody recent history. The escalation was not only in its scale and the ruthlessness of its organisation, but also in its target. Militants in the peninsula have killed hundreds of police and soldiers; the last year has seen them strike Coptic churches and pilgrims further afield in mainland Egypt. Sufi shrines and a 100-year-old cleric have been attacked. But this attack is the first time a mosque there has been targeted (though, like the Mogadishu truck bombing which killed more than 300 people last month, it is a powerful reminder that Muslims are the main victims of attacks by radical Islamist groups).

Much is still unclear and is likely to remain that way, not least because North Sinai has been a closed area since it was put under emergency law in 2014. Though no one has yet claimed responsibility, it is widely assumed to be the work of the Islamic State affiliate, Wilayat Sinai (“province of Sinai”); officials say gunmen carried Isis flags. It may be that the intensity of the backlash, including condemnation from militant groups in Egypt, has deterred the perpetrators from identifying themselves. The motive is still unknown and may be multi-faceted. Isis considers Sufis heretical and one of its propaganda outlets had published an interview with a local commander in Sinai who said that tackling Sufism was a priority. Other reports have suggested the attack could be retaliation against a community that refused to cooperate with the militants, or that a rogue faction could be responsible.

As the rising toll of violence in northern Sinai shows, this is a crisis that has built over decades and accelerated in recent years. The area has been marginalised, neglected and repressed, breeding anger and resentment. Security forces as well as militants have resorted to brutal tactics in communities which they believe may be aiding their foes. Others suggest contributory factors include competition between Isis and al-Qaida; the collapse of neighbouring Libya, where Isis were pushed back but have reportedly been regrouping; and the destruction of the Isis “caliphate” in Iraq and Syria – and the ensuing exodus of fighters and weaponry.

The experience of other countries shows there is rarely an easy explanation for radicalisation. It also highlights the temptation for governments to rush to extraordinary measures, from tightened restrictions to the brute use of force, in staving off terror attacks. Such measures not only contradict the values they seek or purport to uphold, but can also prove counter-productive in fuelling grievances and bolstering militant groups.

Egypt’s president Abdel Fatah al-Sisi was quick to vow “brute force” and vengeance in response to Friday’s attack. Within hours, the government said it had launched airstrikes on “terrorist” locations. The speed of the action itself raised questions for some: if they could be targeted so quickly, they must presumably have been identified before, so why had they not been tackled?

Even his dogged allies in the US, who kept their lips sealed when he ousted the elected Muslim Brotherhood government in a coup in 2013, are understood to have stressed the need for a proper counter-insurgency strategy that goes beyond striking bases – albeit while selling Cairo great quantities of the arms used to target militants (and while Donald Trump appears unstinting in his support for his counterpart). The UK has been more consistent in its message, but for multiple reasons, is unlikely to press too hard. Yet as Alistair Burt, minister of state for the Middle East, pointed out this weekend, confronting such extremism requires tackling it in a variety of ways – including by addressing the underlying causes drawing people towards militancy.

If there are indications that Cairo’s thinking is beginning to take such ideas into account, as some think, the change is not yet obvious on the ground. But relying on brute force is likely to take a further toll on innocent citizens in northern Sinai, and cannot protect them from the kind of attackers who struck al-Rawdah mosque.

• This article was amended on 30 November 2017. An earlier version misspelled al-Rawdah mosque as al-Radwa.

