A Russian airliner blown out of the sky over Sinai, and now the slaughter of Hezbollah’s Shia Muslims in Beirut – it’s the same war.

Thursday night’s suicide bombings by Isis in Lebanon, causing almost 50 deaths and wounding 250, displayed the same savagery, the same attention to detail, the same target: the enemies of Isis who are supporting President Bashar al-Assad’s regime in Syria. The Lebanese were waiting for these latest attacks for weeks.

General Abbas Ibrahim, the head of Lebanon’s “General Security” apparatus, has been saying for months that he is “fighting Isis” – which is perfectly true – and his men, along with the Lebanese army, have for the past two weeks been raiding the homes of Sunni Islamists in Tripoli and around Sidon, reportedly finding explosives and at least one suicide vest. The sinister black Isis flag can now be seen in both Tripoli and hanging over the main street of the Palestinian Ein el-Helwe refugee camp in Sidon.

This does not mean Isis is about to “take over” Lebanon. Nor does it imply a sectarian conflict is about to overwhelm the nation that suffered its own 15-year civil war, which ended a quarter of a century ago. But the Isis struggle against the Russians, Hezbollah, the Iranians, the Syrian regime, President Abdel Fattah al-Sisi’s military rule in Egypt and the Sunni Arab Gulf states will consume the innocent anywhere in the region, and perhaps outside it.

Mourners carry the coffin of the Shia Amal Movement party’s Hussein Hojeij, who died in the blast (Reuters)

Lebanon’s own security apparatus has for months been trying to dislodge an Isis outfit around the Sunni town of Ersal in the far north-east of Lebanon, on the very border with Syria, while General Ibrahim and his colleagues were fearful that Isis might target the huge running marathon in Beirut last Sunday.

Police on bicycles could be seen along the Corniche day and night, talking to gloomy-faced young men with pistols ill-concealed in their trouser pockets, in the hope of preventing an Isis bombing of seafront tourists.

But Isis decided to strike at its old Hezbollah antagonists. It has hit the southern suburbs before, and it almost managed to destroy the Iranian embassy in Beirut when two suicide bombers tried to blast down the gates to the compound.

However, Thursday night’s attack took weeks to plan, according to the same security men who have been trying to prevent such suicide bombings. The two motorcycle bombers must have moved many times through the same Bourj al-Barajneh streets close to the community centre, the market, the bakery and the Hezbollah-run hospital which they eventually targeted.

Lebanese soldiers stand guard at the scene of the attacks (AP)

It’s not easy to move past both the army’s checkpoints at Bourj al-Barajneh and Hezbollah’s own militia barrages. The Isis claim of responsibility was as coldly delivered as its boast of bombing the Russian airliner over Egypt, and Hezbollah, whose thousands of fighters have fought for Assad’s army in Syria – hundreds of whom have paid for this campaign with their lives – delivered its equally bleak reply. This struggle against Isis and its fellow Islamists, Hezbollah said, would be “a long war”.

Lebanon’s own politicians uttered the sort of condemnation that now comes like confetti in a country with a parliament that can scarcely meet because of sectarian squabbling, and with a cabinet that is unable to agree on garbage collection; where the prime minister constantly threatens to resign, and where there has not been a president for a year and a half. There were “plans to create strife”, one minister said, forlornly.