This moment will go down in history: the US has given up on the overthrow of Assad in Syria

When Washington ‘understands the difficult conditions’ its militia allies are facing and says it ‘advises’ the Russians and Syrians not to violate a ceasefire – which was Moscow’s idea in the first place – you know that the Americans are pulling the carpet from beneath another set of allies

If the West is prepared to turn its back on erstwhile allies in southern Syria and in the north, Russia is the winner and all the eggshell militias which remain are doomed (AP)

It will be called the great betrayal. And it was a long time coming. But the grim message from Washington to the anti-Assad fighters of southern Syria – that they could expect no help from the West in their further struggle against Assad’s regime or the Russians – will one day figure in the history books. It’s a turning point in the Syria war, a shameful betrayal if you happen to belong to the wreckage of the “Free Syrian Army” and its acolytes around the city of Deraa, and a further victory for the Assad regime in its ambition to retake all of rebel Syria.

Already Russian missiles and Syrian bombs are embracing the countryside south and east of Deraa and outside Quneitra and Sweida after the opposition fighters refused a negotiated peace last week. Refugees are again fleeing the towns. But the words of the American message to the fighters, seen by Reuters and so far not denied by the US, are both bleak and hopeless: “You should not base your decisions on the assumption or expectation of a military intervention by us … We in the United States government understand the difficult conditions you are facing and still advise the Russians and the Syrian regime not to undertake a military measure that violates the [de-escalation] zone.”

When Washington “understands the difficult conditions” its militia allies are facing and says it “advises” the Russians and Syrians not to violate a ceasefire – which was Moscow’s idea in the first place – you know that the Americans are pulling the carpet from beneath another set of allies.

But the US also realises that its millions of dollars worth of training and weapons have been passed on to al-Nusra – aka al-Qaeda of 9/11 infamy – and that the Nusra front holds villages and positions within the area outside Deraa nominally held by those well-known “moderates” of the FSA (whose mythical strength, you may remember, was once put at 70,000 by one David Cameron).

Neither the Hezbollah nor the comparatively fewer Iranian Revolutionary Guards appear to be involved in the battle for southern Syria; and be assured that the Americans and the Russians – and thus the Syrian government – have agreed that this should be a Russo-Syrian offensive. Both Vladimir Putin and whoever thinks they speak for Donald Trump will have assured the Israelis that this will be an internal battle and will not endanger the Israeli-occupied Syrian Golan Heights. The so-called Military Operations Centre in Amman – its acronym “MOC” almost sums up its ambitions – is supposed to arm and finance the group of militias still fighting in north of the Jordanian border. But no more, it seems.

The Israelis have hitherto attacked Syrian and Iranian targets in Syria – but never the cult-Islamist Isis executioners nor Nusra/al-Qaeda. US policy, despairing of ever “collapsing” Assad, now appears to have given up on the armed opposition to the Damascus government, presumably advising Israel that a return to the status quo on Golan which existed before the Syrian war – where Israeli and Syrian forces were separated by a UN buffer zone – is preferable to risking a shootout with Iran or, indeed, with the Syrian army.

The MOC, according to a former opposition fighter in Damascus, chose to control all rebel activities – in theory, the “FSA” – and specifically refused help four years ago when fighters in the capital sought mortars and artillery to assault the presidential palace. The MOC officers – a British major and a Saudi officer, according to the source – offered only a resupply of small arms. But this was only a warning of things to come. The Kurds have since learned what this means in the north of Syria.

They, of course, have twice supped from the vile chalice of betrayal. Kissinger served it up to them when he made peace between Saddam Hussein and the Shah of Iran in 1975, cutting off a $16m (£12m) CIA operation to help the Kurds assault the Iraqi dictator. Then the Americans watched Saddam destroy the Kurds in 1991 after telling them to rise up against the Baghdad regime following the liberation of Kuwait.

Syria fears that the Israelis will now create their own “buffer zone” below Golan, similar in style, weaponry and ruthlessness to Israel’s former occupation zone in southern Lebanon. This lasted for 22 years, but fell to pieces when Israel’s local Lebanese militia, the South Lebanon Army – as inefficient, untrustworthy and occasionally as fictitious as the “Free Syrian Army” – retreated along with the Israelis in 2000.

Across the map of Syria, however, it is the West’s power which now appears to be in retreat. If it is prepared to turn its back on its erstwhile allies in southern Syria and in the north, then Russia is the winner (as well as Assad) and all the eggshell militias which remain – in Idlib, along the Turkish border and certainly in the south, are doomed. The instruction from the US to its allies outside Deraa – “surrender” might sum it up best – may be presented as a small victory: Washington can claim to have kept Iran away from Israel. But it will also mean that America and Nato have given up on the overthrow of the Assad family.