Between last Thursday and Monday, the Turkish government, in league with Saudi Arabia, made a tentative decision to enter the war on the ground in Syria - and then got cold feet about it. Or more likely, the Turkish army simply told the government that it would not invade Syria and risk the possibility of a shooting war with the Russians.
The Turkish government bears a large share of the responsibility for the devastating Syrian civil war. From the start, Turkey's leader Recep Tayyip Erdogan was publicly committed to overthrowing the Syrian regime of Bashar al-Assad. For five years he kept Turkey's border with Syria open so that arms, money and volunteers could flow across to feed the rebellion.
Erdogan's hatred of Assad is rooted in the fact that he is a militant Sunni Muslim while Assad leads a regime dominated by Shia Muslims. Both men rule countries that are officially secular, but Erdogan's long-term goal is to impose Islamic religious rule on Turkey. Assad is defending the multi-ethnic, multi-faith traditional character of Syrian society - while also running a brutally repressive regime. Neither man gives a fig for democracy.
Saudi Arabia has been Erdogan's main ally in the task of turning Syria into a Sunni-ruled Islamic state (although 30 per cent of Syrians are not Sunni Muslims). Together these countries and some smaller Gulf states subverted the original non-violent movement in Syria that was demanding a secular democracy, and then armed and supplied the Sunni-dominated armed rebellion that replaced it.
The US government also wanted to see Assad's regime destroyed (for strategic reasons, not religious ones). So for years Washington turned a blind eye to the fact that its allies, Turkey and Saudi Arabia, were actually supporting the extremists of Islamic State (Isis) and the Nusra Front, al-Qaeda's franchise in Syria.
Largely as a result of that support, these two extremist organisations now completely dominate the Syrian revolt against Assad's rule, accounting for 80-90 per cent of the active fighters. Turkey and Saudi Arabia finally broke their ties with Islamic State last year, but they still back the Nusra Front, which has camouflaged itself behind an array of minor "moderate" groups in the so-called "Army of Islam".
When the Nusra Front, with strong Turkish support, overran much of northwestern Syria last spring, Russia finally went to the aid of its long-standing ally, the Syrian government. Russian air power helped the Syrian army push back the troops of both the Nusra Front and Islamic State. Erdogan pushed back, ordering Turkish fighters to shoot down a Russian bomber last November.
Even at the time, however, it was clear that the Turkish army was very unhappy about the prospect of a military clash with Russia. It doesn't share Erdogan's dream of an Islamist-ruled Syria either. Meanwhile the Russian bombs kept falling, the Syrian army went on advancing, and now it has cut the main supply line from Turkey to the rebels in and around Aleppo.
Erdogan is frustrated and angry, and he now has an equally reckless ally in Prince Muhammad bin Salman, the Saudi deputy Crown Prince and defence minister. Over the past week these two men appear to have talked themselves into a limited military incursion into Syria to push the regime's troops back and reopen the supply lines to the rebels.
On Sunday the Turkish army began shelling Syrian Kurdish forces. On Monday Assad's government complained to the UN that about a hundred "Turkish soldiers or mercenaries" had crossed the border into Syria. But at that point the grown-ups took over, and the Turkish defence minister denied that there was any intention to invade Syria.
France publicly warned Turkey to end its attacks, and there were doubtless secret but frantic warnings to the same effect from Turkey's other Nato allies. Turkey (and Saudi Arabia) have almost certainly been put on notice that if they choose to start a local war with Russian forces in Syria, they will have to fight it alone.
So that is probably the end of that, and everybody can get back to the business of partitioning Syria - which is what all the talk of a "cessation of hostilities" is really about.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries.
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