As the two leaders settled down for the Olympic judo, news came in that Kofi Annan had resigned as UN envoy for Syria

Vladimir Putin and David Cameron were never likely to have a meeting of minds on the Syrian crisis. But since the violence is getting worse by the day and diplomacy is failing it was probably worth a try to see if Russia might agree to get just a bit tougher with Bashar al-Assad.

Kofi Annan's shock resignation as the UN envoy for Syria – announced as the prime minister and president were watching the judo at the Olympic stadium in London – underlined how bad things now are internationally.

Downing Street had wisely gone for low expectations, making clear in advance of their meeting that the issue was a tough one and substantive progress was unlikely. Putin, after all, remains Assad's most important supporter. He has used Russia's UN security council veto three times to block any punitive action against Syria during the 17 months of the uprising.

Their differences, then, were entirely predictable, as was the reflexive diplomatic attempt by both leaders to accentuate what little they had in common. "We both want to see an end to (the) conflict and a stable Syria," Cameron insisted after their 45-minute meeting. Putin said the UK and Russia saw "eye-to-eye" on aspects of the situation and would work together to find a viable solution.

Exactly how they will do that is unclear since there is no disguising how far apart they are. Last time Russia said "nyet" at the UN, the UK lambasted it as "inexcusable and unforgiveable" That was to block unspecified UN sanctions if Assad failed to implement his side of the six-point plan Annan had been trying to broker on behalf of the UN and the Arab League. So even without a hint of a repeat of Nato's military intervention in Libya last year, the Russians refused to put any pressure on Damascus.

Cameron's pitch to Putin was the same one that is being used by the US and other western countries: Assad's days are numbered, they argue, as events spiral rapidly out of control into a fully-fledged civil war that could suck in outsiders from Iran to Israel, trigger a huge humanitarian crisis and serve as a magnet for jihadis. Moscow, this argument goes, would be wise to consider its long-term regional interests. Russia is already seen as an outright enemy of the Syrian revolution. Without a swift change of tack it seems certain to lose its prized naval base at Tartous on the Mediterranean as well as lucrative arms sales.

Russia responds by accusing the west of hypocrisy by effectively supporting regime change in Damascus – though the Annan plan called for a Syrian-led political transition – while turning a blind eye to rebels who are being supported by the US and its allies and financed and armed by Saudi Arabia and Qatar with help from Turkey. It bridles at suggestions that it and fellow veto-wielder China are to blame for disarray over the crisis.

The only practical consequence of the meeting was to agree that the foreign secretary, William Hague, and his Russian counterpart, Sergei Lavrov, are to meet. Nothing appears to have changed since Cameron and Putin last met in Mexico in June. At the end of that meeting the prime minister insisted that Putin "does not want Assad remaining in charge in Syria". That remains, for now at least, more wishful thinking than an accurate guide to the current harsh realities.

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