The extraordinary destruction of a Syrian fighter jet by a US aircraft on Sunday has precious little to do with the Syrian plane’s target in the desert near Rasafa – but much to do with the advance of the Syrian army close to the American-backed Kurdish forces along the Euphrates. The Syrians have grown increasingly suspicious in recent months that most Kurdish forces in the north of Syria – many of them in alliance with the Assad government until recently – have thrown in their lot with the Americans.

Indeed, the military in Damascus is making no secret of the fact that it has ended its regular arms and ammunition supplies to the Kurds – it has apparently given them 14,000 AK-47 rifles since 2012 – and the Syrian regime was outraged to learn that Kurdish forces recently received an envoy from the United Arab Emirates.

There is unconfirmed information that a Saudi envoy also visited the Kurds. This, of course, follows the infamous Trump speech in Riyadh, in which the US President gave total American support to the Saudi monarchy in its anti-Iranian and anti-Syrian policies – and then later supported the Saudi-led isolation of Qatar.

On the ground, the Syrian army is now undertaking one of its most ambitious operations since the start of the war, advancing around Sueda in the south, in the countryside of Damascus and east of Palmyra. They are heading parallel with the Euphrates in what is clearly an attempt by the government to “liberate” the surrounded government city of Deir ez-Zour, whose 10,000 Syrian soldiers have been besieged there for more than four years.

Donald Trump says Iran has helped commit 'unspeakable crimes' in Syria

If they can lift the siege, the Syrians will have another 10,000 soldiers free to join in the recapture of more territory. More importantly, however, the Syrian military suspects that Isis – on the verge of losing Raqqa to US-supported Kurds and Mosul to US-backed Iraqis – may try to break into the garrison of Deir ez-Zour and declare an alternative “capital” for itself in Syria.

In this context, the American strike on Monday was more a warning to the Syrians to stay away from the so-called Syrian Democratic Forces – the facade-name for large numbers of Kurds and a few Arab fighters – since they are now very close to each other in the desert. The Kurds will take Raqqa – there may well have been an agreement between Moscow and Washington on this – since the Syrian military is far more interested in relieving Deir ez-Zour.

The map is quite literally changing by the day. But the Syrian military are still winning against Isis and its fellow militias – with Russian and Hezbollah help, of course – although comparatively few Iranians are involved. The US has been grossly exaggerating the size of the Iranian forces in Syria, perhaps because this fits in with Saudi and American nightmares of Iranian expansion. But the success of the Assad regime is certainly troubling the Americans – and the Kurds.

So who is fighting Isis? And who is not fighting Isis? Russia claims it has killed the terrible and self-appointed “caliph of the Islamic State”, al-Baghdadi. Russia says it is firing Cruise missiles at Isis. The Syrian army, supported by the Russians, is fighting Isis. I have witnessed this with my own eyes.

Aleppo before the Syrian Civil War Show all 12 1 /12 Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man crosses a street in Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A vendor sits inside an antique shop in al-Jdeideh neighbourhood, in the Old City of Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, overlooking Aleppo city, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors walk inside Aleppo's Umayyad mosque, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk inside the Khan al-Shounah market, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man walks past shops in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk along an alley in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors tour Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A general view shows the Old City of Aleppo as seen from Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk near Aleppo's Bab al-Faraj Clock Tower, Syria October 6, 2010 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man stands inside Aleppo's historic citadel, overlooking Aleppo city, Syria December 11, 2009 Reuters

But what is America doing attacking first Assad’s air base near Homs, then the regime’s allies near Al-Tanf and now one of Assad’s fighter jets? It seems that Washington is now keener to strike at Assad – and his Iranian supporters inside Syria – than it is to destroy Isis. That would be following Saudi Arabia’s policy, and maybe that’s what the Trump regime wants to do. Certainly, the Israelis have bombed both the Syrian regime forces and Hezbollah and the Iranians – but never Isis.