No one could have predicted the gruesomely random turn that the east Ukraine conflict took last week. When the first rumours about a Malaysian passenger flight going missing broke on Thursday afternoon, it was the kind of moment that led to double takes.

Journalists, officials and people around the world shook their heads and tried to grasp the enormity of what had happened: nearly 300 people with nothing to do with eastern Ukraine, settled into their seats to eat and watch movies, had been blown out of the sky, possibly because somewhere six miles below them a rebel had thought their jet was a Ukrainian plane filled with "Kiev fascists".

As hundreds of families in the Netherlands, Malaysia, the UK and around the world come to terms with personal tragedies, and as international investigation teams attempt, so far unsuccessfully, to reach the location of the debris, there is also the question of what comes next politically. What does the tragedy of MH17 mean for the conflict in eastern Ukraine and, by extension, for Russia's relations with Europe and the US?

Predicting what happens next in the confusing maelstrom that is 2014 Ukraine has been a fool's game so far. Who could have imagined in early February that by the end of the month former president Viktor Yanukovych would have fled, leaving those who had led the Maidan protests to take up the running of the country? Who, then, would have expected that Vladimir Putin's response would be the cynical and clinical grab of Crimea? And even after Crimea, it appeared inconceivable that what initially looked like mild discontent in eastern Ukraine could turn into a full-blown civil war.

Now the eventual consequences of this latest and most implausible twist in the tale are equally hard to predict. Much will depend on what exactly 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 most certainly has some local sympathy and some local personnel, but the leaders have Russian passports, travel to Moscow to meet Kremlin officials and are equipped with weapons and training that come from Russia. Privately, some Russian officials admit this and justify it by suggesting that the west behaved no differently when it "engineered" the Maidan protests in Kiev. Publicly, however, they have felt comfortable claiming that 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 the allegations it voiced on Saturday – that the Buk missile system it believes downed MH17 crossed the border from Russia together with three specialists who knew how to use it. It may be that some western leaders will actually be relieved at the possibility of allowing Russia to cling to a thread of deniability.

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. Barack Obama was quick to say that 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" remains unclear, but perhaps the biggest and most unpredictable variable in the equation is how Putin himself reacts. Oh to be a fly on the wall in the meetings currently going on in the Kremlin's inner sanctum.

Putin, when he first appeared after the crash at an gathering of economics officials on Thursday evening, looked furious as he blamed Ukraine for the tragedy. He carefully avoided speculating about who fired the missile, but said it was clear that the country over whose airspace the tragedy had happened was responsible for it (presumably we should blame the US for 9/11).

Analyst Stanislav Belkovsky says it is obvious from Putin's tone and body language that he was absolutely furious and "filled with negative emotions" during this appearance. If it was the rebels who downed the plane, Putin is in a difficult personal dilemma.

The president has a visceral disgust for terrorist methods that is quite genuine. Not for him nuanced discussions of the socioeconomic causes of terrorism, or empathy about what might lead people to commit unthinkably horrific acts. He came to power promising to "waste" Chechen terrorists "in the outhouse", and did pretty much exactly that. He showed obvious sympathy with George W Bush in the aftermath of 9/11, and for all Russia's links with the Arab world has given tacit support to Israel over the way it deals with terrorism.

All of this makes it grimly ironic that – if the suspicions are correct – Putin's government has at the very least enabled one of the most deadly terrorist acts of all time. While there was almost certainly no intent to bring down a passenger liner, it will 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 in Britain and 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. Instead, state television is scrambling to promote outlandish conspiracy theories, or suggesting as Putin did that Ukraine is ultimately responsible for the tragedy, whoever fired the missile. The deputy foreign minister has railed that the US is like a "bad surgeon", wandering around the world making crude incisions and then being surprised by the pain that ensues. The minor issue of who actually brought down the plane, in this version, is almost an irrelevance.

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 a gruesome air tragedy, and it would be a brave person who predicts exactly what the outcome will be.