How much longer will Russia continue to prop up the discredited and bloodstained regime in Syria? That question was surely high on the agenda yesterday in Istanbul, where Vladimir Putin, the president of Russia, conferred with the Turkish prime minister, Recep Tayyip Erdogan.
It is easy to imagine what Mr Erdogan might have said: "For over 18 months you have given comfort and political cover to Bashar Al Assad as he has systematically targeted children and civilians while repressing first protests, then a revolt, and now open civil war. You have sheltered him from international action through the UN, tolerated his excesses, tried to send him helicopters and radar gear and possibly weapons. You are even printing his banknotes, after EU sanctions stopped the Austrian company that used to make them.
"And while you do this," Mr Erdogan might have continued, "the regime has subjected Syrian society, and the country's economy and infrastructure, to ever-growing damage. And the factional and sectarian violence is leaking into neighbouring countries, including Turkey.
"If you had sent the right signal to Syria's elite, say 16 months ago, then the regime, left friendless, would have been compelled to permit reforms or even change leaders. All this could have been averted. But now your protégé is at the end of the line. The rebels are closing in, and the Assads will have to flee or die. When are you going to do the right thing?"
In reality, Mr Erdogan may not have been as blunt as we like to imagine; Turkey needs more Russian natural gas this winter, for one thing. But the people of Syria, and of the world, are saying the same thing to the Russians, and by now Mr Putin's own advisers may be in the chorus as well.
By its support for the Assad elite, Russia has badly damaged its own reputation in the Arab world, which feels Syria's agony deeply. But Mr Putin has trapped himself. This week Gennady Gatilov, Russia's deputy foreign minister, called yet again for "broad national dialogue" leading to a political settlement in Syria. This has been Moscow's consistent line, which in practice means doing nothing meaningful.
The time for compromise with the Assad regime is long gone; far too many Syrians have been tortured or murdered; their grieving kinsmen cannot compromise with the killers.
There is tragedy in Russia's stance, too: if Mr Putin had used Moscow's leverage with the Damascus government 15 or 18 months ago, by really pushing the Assad regime, much of Syria's agony might have been averted. Bashar Al Assad is not the only culprit in all this.