This is the first time in more than 50 years a Nato plane has shot down a Russian plane, and it happened in very suspicious circumstances.
Even if Turkish radar data is to be believed, the two Russian SU-24s only crossed the bottom of a very narrow appendix of Turkish territory. As Russian President Vladimir Putin said: "Our pilots, planes did not threaten Turkish territory in any way." What harm could they have done in 17 seconds?
According to Russian radar data, it was the Turkish planes that crossed into Syrian territory. And how strange that there was a Turkish TV crew in northern Syria, positioned just right to film the incident (the Russian plane crashed 4km inside Syria).
Either way, it seems clear President Erdogan wanted to shoot down a Russian aircraft and that Turkish pilots were under orders to do so on even the slightest pretext.
President Putin said Erdogan and his colleagues were "accomplices of terrorists". That's hard to deny - Erdogan is so eager to see Syria's President Bashar al-Assad overthrown that he left the Turkish-Syrian border open for four years so recruits and supplies could reach Syrian rebel groups, including Islamic State (IS).
Black-market oil is Islamic State's largest source of revenue, and almost all of it goes to Turkey, which could not happen without the Turkish government's connivance.
Erdogan is utterly determined Assad must go, and he doesn't care if Assad's successors are Islamist extremists. He also wants to ensure there is no new Kurdish state on Turkey's southern border.
That state already exists in embryo. It is called Rojava, a territory Syrian Kurds have carved out in the far north along the Turkish border, mainly by fighting Islamic State.
When Erdogan committed the Turkish air force to the Syrian war in July, he said it was to fight Islamic State, but in fact Turkey has made only a token handful of strikes against IS. Almost all Erdogan's bombs have actually fallen on the Turkish Kurds of the PKK (who had been observing a ceasefire with the Turkish government for the past four years), and above all on the Syrian Kurds. Erdogan has two goals: ensure the destruction of Assad's regime and prevent the creation of a new Kurdish state in Syria. He was making some progress, then along came the Russians in September and saved the Syrian army from defeat. Worse yet, Putin's strategy turns out to be quite pragmatic, and even rather attractive to the United States. Putin wants a ceasefire in Syria that will leave everybody where they are now - except Islamic State, which they can all then concentrate on destroying.
This strategy is abhorrent to Erdogan because it would leave Assad in power in Damascus, and give the Syrian Kurds time to consolidate their new state. How can he derail this Russian-led project? Well, he could shoot down a Russian plane, and try to get a confrontation going between Russia and Nato.
-Gwynne Dyer is a journalist whose articles are published in 45countries.
