The Syrian civil war could spill over far beyond its borders according to senior Israeli military sources, leading to fears that jihadis could “sweep through the region”.

Military analysts also believe that no end is remotely in sight to the conflict and that it could last for 15 years.

The Israelis see Jordan as the “buffer” against Syrian jihadis and if the Hashemite Kingdom is not given sufficient help to cope with the daily influx of 3-4,000 Syrian refugees, the Israeli military believes it could collapse.

According to military analysts, Syria is now the cause of a dangerous and unprecedented regional instability, having for decades been one of the main forces for stability.

The Russians — and the Iranians — are believed by the Israelis to be supplying the Syrian regime with arms “by the week”.

A source said: “It is impossible now to see how Syria will be stable again.

“Because of Russia’s involvement, this is not just a regional issue but a superpower issue.”

The Israelis’ immediate concern is the ownership of Syria’s chemical and biological weapons. There is, they believe, a “strong risk” of such weapons falling into the hands of Hezbollah.

This should concern all governments: “The key point about Hezbollah is that it does not just operate in Lebanon and Syria. It is developing in Africa, has already killed in Bulgaria and is growing its terrorist capabilities in Europe.”

In the Israeli military’s view, the twin key dangers facing Israel are an Iranian victory in Syria and its potential nuclear bomb. These are seen as being interlinked; victory in one sphere will make Iran more confident in the other.

Although the West is increasingly committing itself to backing the rebels in Syria, the Israelis are wary of handing weapons over to jihadis. But they also believe that Bashar al-Assad is “no longer the devil we know. He is now a new devil”. It is more a case of the bad versus the bad, for Israel.

The best outcome they hope for would see Syria governed by a regime that “behaves responsibly and is supported by the West, and exists without Iran and the jihadists”.

But even in the most optimistic scenarios, the Israeli military believes that the conflict in Syria could last as long the Lebanese Civil War, which began in 1975 and did not end until 1990.