Meetings between heads of government have become commonplace. But Monday's between Presidents Barack Obama and Vladimir Putin is something special.

They have not met formally for nearly two and a half years. The last encounter, planned, for August 2013, was brusquely cancelled by Obama because “there was nothing to talk about”. The main undiscussable issue was Syria. The United States wanted President Assad instantly out; Russia feared chaos without him. The Ukraine crisis pushed the relationship further downhill. Russia, seeing a Western attack on its interests, responded by seizing Crimea and supporting separatist war in eastern Ukraine. The West retaliated with tough sanctions. Even co-operation to achieve this year’s Iran agreement (which needed Russian Security Council assent) did not lift the Obama/Putin chill.

So tomorrow’s meeting is a dramatic reversal. Already the two sides are spinning it differently. The Americans say the Russians were “desperate” for it, while the Russians say it was by mutual consent. And the Americans say it will be all about Obama taking Putin to task over Ukraine, while the Russians say the main item of business will be Syria.

In fact, behind the misleading briefings, it is plainly the build-up of Russian troops in Syria that has precipitated the meeting. Western commentators have offered the normal range of fanciful explanations for this: to replace the fading US presence in the region, or to put pressure on the Saudis over oil prices. The reality is simpler. As Putin says (and on this is to be believed), Russia’s overriding aim is to block the rise of Islamic fundamentalism which is a direct domestic threat to them in the Caucasus and elsewhere. They have seen the West bungle this, notably by the chaos left behind in Iraq and Libya. The West’s support for a moderate opposition in Syria is a delusion (didn’t the responsible US general tell Congress a few days ago that that opposition had “four or five” US-trained soldiers in the field?). The only choice in Syria is between the nasty (Assad) and the nasty and dangerous (Islamic State). Unconstrained by public opinion or any concern for human rights, this is a no-brainer for Putin. He is bolstering the faltering Assad to prevent IS inheriting Syria. And, he adds, the West, which is as threatened by IS as Russia, should join him.

Western policy does seem to be moving the way Putin wants. The US and (as of Friday) the UK, having spent years demanding Assad’s instant departure, now concede that he might stay on in an “interim” capacity. The US Defence Secretary, after a year of refusing contact with his Russian opposite number, opened such contact last week in order to “deconflict” the two countries’ actions on the ground. Whatever the obfuscations around tomorrow’s meeting, Syria will be a key part of the agenda.

Obama will also tackle Putin on Ukraine. But here, too, it looks as though the debate is moving in Russia’s direction. In February this year, when the Minsk II Peace Agreement was signed as the basis for a ceasefire and political settlement, both the US and the UK were dismissive. The agreement, we quietly said, would rapidly collapse. Our policy remained to “change Putin’s calculus”, meaning to use sanctions to compel Russia to back down. But this has not worked. With all its imperfections, Minsk has in fact helped to end the fighting, and is still very much in play. And, while the sanctions have done some economic damage, they have not changed one jot Putin’s determination to retain Crimea and the whip hand in eastern Ukraine. On the contrary, they have cemented Russian public opinion firmly behind him. The avowed aim of sanctions has therefore quietly shifted to ensuring Russian observance of Minsk. When Obama says this to him tomorrow, Putin can only agree. He wants Minsk to work, too. He has got roughly what he wants in Ukraine and hopes now to get back to a more normal relationship with the West.

The Ukrainian crisis is not over. We are in for some rough moments this autumn. The political provisions of Minsk will begin to fray as the two Ukrainian sides continue to refuse to talk to each other. The official report on the downing of the Malaysian airliner, due next month, will almost certainly blame the rebels, and provoke a storm of further criticism of Russia. And the end-of-year deadline for closing the Russian/Ukrainian border will certainly not be met. But the major players are now talking rather than shooting. While we are not yet out of the tunnel, we may well be approaching the exit ramp.

The choice is between the nasty (Assad) and the nasty and dangerous (IS). For Putin, a no-brainer’ <p> </p>

So is Russia on a roll? Sensible Russians will welcome their country’s foreign policy successes, but also have real worries. The danger of the Putin regime, unconstrained by public opinion or parliament, overconfidently blundering into some further foreign adventure is high. And Russia’s core problem, its underperforming domestic economy, remains acute. There is no sign of any will to tackle the corrupt clientelism that keeps Russia poor and earns public detestation. Politically sensitive public benefits, such as pensions, are under pressure. Next year brings parliamentary elections whose outcome can be massaged but not entirely fixed. Putin’s real nightmare is not Western sanctions but Goldman Sachs’ prediction that the oil price could fall to $20 a barrel. The support of his people is at the moment overwhelming, but how long can it last if living standards collapse?

Nevertheless, Vladimir Putin may recall Madeleine Albright’s description in 1998 of the US as the “indispensable nation”, vital to tackling the world’s problems. And he may take some pleasure in his discussion with Barack Obama in noting that, for some of those problems – Iran, Syria, Ukraine – Russia, too, is indispensable.