Leading article: A Cold War replay that speaks of warmer East-West relations

On one of the hottest days of the year, the scene at Vienna airport recalled some of the coldest days of the Cold War. Two planes, one flown in from New York, the other from Moscow, stood side by side on the tarmac. There was an exchange; the planes flew back with new passengers, and there was quiet satisfaction with a deal well done.

Those who negotiated the arrangements that resolved the case of the Russian "illegals" must have been either veterans of spy swaps past or well-schooled in Graham Greene, and with a sense of humour to boot. Although the charges brought by the US authorities had fallen short of espionage, all 10 individuals were required to admit their guilt. The same applied in Moscow. Admitted culpability and an official pardon completed the validation required for the exit ticket. The choice of Vienna, a city nestled right up against the Iron Curtain that positively seethed with foreign agents in its day, suggested something almost like nostalgia.

If the scene was vintage Cold War, however, the political atmosphere was not. From the day this bizarre story broke, with the arrest of 10 people living under assumed identities in the US, officials in Washington and Moscow seemed at pains to keep a distance. When anything was said publicly on either side, it was to insist that this episode should not be allowed to derail improving ties. The time that elapsed between the first revelations and this, the largest exchange of spies for almost half a century, broke all records for an exchange of secret agents. There had to be political will at the highest level on both sides to make it happen.

Yesterday's sunlit exchange was a world away from the pre-dawn gloom, armed guards and stony faces that were in evidence 24 years ago when Natan Sharansky walked across Berlin's Glienicke bridge in exchange for two Czech spies. In yesterday's swap it was almost possible to detect an air of cordiality; relief perhaps, too, that there are still people around who remember how such things are done.

This tale, of course, has a serious side. At least one of the 10 Russians appears to have no link beyond marriage with Russia; she may find herself marooned, perhaps for ever, in a foreign land. And what of the children, brought up to think of themselves as American? There are many lives here, including innocent ones, which have been turned upside down. It could also be objected that the deal was one-sided. But the US and Britain secured the freedom of four people who were serving long prison sentences in Russia and a bargain is about substance as well as numbers. As for the appearance of condoning spying, there are times, as there were during the Cold War, when pragmatism must be allowed to outweigh principle, for the greater good.

It would probably be too optimistic to see yesterday's denouement as equivalent to a piece of sympathetic magic that could serve to banish the Cold War for good. Espionage, one way or another, will remain a fact of international life. But the determination of both Moscow and Washington – and perhaps London, too – to settle this case without acrimony is the most persuasive sign so far that President Obama has pressed the reset button with Russia to positive effect.