Russian leader openly hostile to terror acts but government may have just enabled one of deadliest of all time.
What does the tragedy of MH17 mean for the conflict in eastern Ukraine and for Russia's relations with Europe and the US?
Much will depend on what can be ascertained by any investigation. At the moment, plenty of circumstantial evidence points to MH17 being downed by the rebels, possibly using a weapon provided by Russia. But if a "smoking gun" is not found - and with every hour that the crash site is contaminated and not handed over to proper investigators, the chances of a thorough investigation seem to diminish - the Russians may be able to mount a plausible deniability defence.
This, after all, has been a conflict where plausible deniability has been stretched beyond belief.
Both sides have been at it - the Ukrainians have shelled residential areas while claiming to have no idea such things were happening - but the Russians have turned it into an art form.
The insurgency has some local sympathy and some local personnel, but the leaders have Russian passports, travel to Moscow to meet Kremlin officials and have weapons and training from Russia. Privately, some Russian officials admit this and justify it by suggesting the West behaved no differently when it "engineered" the Maidan protests in Kiev. Publicly, however, they have felt comfortable claiming this is a purely local affair and rebuffing all suggestions that "volunteer" fighters were trained and armed in Russia.
It may be that Ukraine can never prove its allegations that the Buk missile system it believes downed MH17 crossed the border from Russia together with three specialists who knew how to use it.
Western officials so far have grimly insisted that Putin "must" stop the rebels and "must" allow access to the crash site, but there has been little of substance appearing in the "or else" column. US President Barack Obama said military options were not on the table, though further enhanced economic sanctions appear likely. To what extent the West has the appetite for a true "new cold war" is unclear.
But if the rebels downed the plane, Putin is in a difficult personal dilemma. The President has a visceral disgust for terrorist methods that is quite genuine. He came to power promising to "waste" Chechen terrorists "in the outhouse", and did pretty much exactly that. It would be a devastating blow to Putin if it proves that "his" people were guilty of this act.
However it seems likely that far from prompting introspection and apologies, MH17 will only serve to intensify the Russian sense of belligerence and unfair victimisation that has become more pronounced as 2014 has gone on, with criticism of the Sochi Winter Olympics and the annexation of Crimea bundled into one and served as incontrovertible proof of pathological Russophobia in the West. The slew of "Putin the killer" front pages across Europe are likely to exacerbate this. Early signs seem to suggest that Russia is not preparing to abandon the rebels and publicly denounce their methods.
What happens next will be decided by the results of the investigation, if it goes ahead, and by decisions in Kiev, Moscow and Western capitals. But Ukraine in 2014 has seen revolution, annexation, civil war and now an air tragedy, and it would be a brave person who predicts exactly what the outcome will be.