If British and American intelligence agencies are correct in their suspicion that a bomb on board brought down the Russian plane that crashed in Egypt’s Sinai peninsula last week, it would mark an important moment for the rapidly evolving jihadist threat.

For one thing, it would be the first such attack since Chechen bombers destroyed a pair of Russian aircraft in 2004. While attention has been on possible missile attacks, like that which bought down Malaysia Airlines Flight 17 over Ukraine in 2014, al-Qaeda’s branch in Yemen (AQAP) has been making technological strides in the development of undetectable, non-metallic bombs. AQAP attempted two failed attacks using an underwear bomb and even a rectal bomb in 2009 and smuggled explosives aboard US-bound cargo planes in 2010. A Saudi double agent inside AQAP even retrieved one such device in 2012, but the group boasted of a new design last December.

The novelty would be if the Islamist militants of Isis, rather than AQAP, had been the ones to actually succeed. Al-Qaeda and Isis are now bitter rivals, having acrimoniously split up early last year. If Isis was responsible, there is of course every chance that such an attack succeeded because of lax security procedures rather than any novel bomb design.

An attack would not necessarily represent a strategic shift. It is true that, unlike al-Qaeda, which focused on spectacular attacks worldwide, Isis has concentrated its energies on the core territory of its self-declared caliphate in Syria and Iraq. But it has also claimed several foreign wilayats (provinces) from Algeria to Pakistan, typically grafting its brand on to local groups rather than setting up from scratch. It has also encouraged supporters to carry out independent attacks, although these have had only tenuous connections to the Isis leadership.

The group’s local ally in Egypt, the 1,000-strong Sinai Province, has conducted dozens of assassinations and bombings, including on foreign nationals. There is not necessarily a huge difference between an Isis-linked group killing Britons in Tunisia, as was the case in June, Turks in Ankara in a bomb attack last month, and now perhaps Russians in Egypt. All represent mass-casualty attacks on foreign targets. The key question that intelligence officials will be looking at is whether this is another case where Isis merely cheered on from the sidelines, offered limited assistance and took vocal credit — or whether their involvement runs deeper and points to growing ambitions.

Finally, events in Egypt could have a knock-on effect in Syria. If it is confirmed that a bomb did bring down Kogalymavia Flight 9268, and that Isis or one of its allies was responsible, the irony is that Vladimir Putin could be pressed into actually doing what he has been pretending to do for a month: directly targeting Isis in Syria. One month and a 1,000-plus air strikes into its intervention there, Moscow has dropped over 90 per cent of its bombs on areas where Isis has little known presence. Instead, it has focused on more moderate rebel groups fighting the regime of Bashar al-Assad, including many backed by the US. But pressing Isis harder could bring Russian jets into closer proximity to the US-led coalition.

Moscow might also use the incident as justification for growing its presence in Syria, which now comprises 4,000 personnel. That could further constrain the west’s own options and massively amplify the already growing refugee flow. So far, Russia’s only response has been to send more anti-aircraft missiles to Syria: a bizarre step, given that shooting down planes will not achieve much. But if the official investigations point towards Isis, we could see things move quickly.

The writer is a senior research fellow at the Royal United Services Institute

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