Summits need tact, not insults

The most important point first: it is better that the leaders of 20 of the world's main countries should meet from time to time and talk than that they should stay at home and hurl insults at each other from a distance.

The history of global summitry has been, mostly, a history of progress. The G3 in the 1970s, which grew to the G8 and was superseded by the G20 in London in 2009 – the summit that "saved the world" – has seen the world grow richer and freer as its population doubled. Summits have played a small part in that, but they have helped to co-ordinate economies at the margins, to ease tensions and to set common goals.

Much of the unsteady progress towards action on climate change, for example, has come from the ratchet effect of leaders committing their nations to targets and timetables at summit meetings. It was not central to the G20's business in Brisbane this weekend, but the shifts in the positions of the US and of China on global warming are partly the result of the peer pressure exerted by international powwows such as this.

As for the world economy, ostensibly the main business of the summit, Hamish McRae argues today that the meeting "will do no harm, and that is more than can be said for a lot of economic policy in recent years".

The main drama yesterday, however, was provided by Vladimir Putin's interactions with other leaders over Russian aggression in Ukraine. It may be naive to hope that the Russian President's attendance at the summit in Australia might act as a restraint on his policy of trying to annexe more parts of Ukraine, but we can be confident that, if Mr Putin were not at the G20, the prospect of exerting moral pressure would be diminished.

Russian domestic opinion, which is strongly behind Mr Putin's assertive foreign policy, wants to see him take his place on the world stage as a respected equal of Russia's old rivals. This gives Western leaders some leverage. They have tried to use it by a combination of cold shoulder and dialogue. Russia has been suspended from the G8, the smaller body which is now less important than the G20, and Mr Putin has been given such a hard time by his fellow leaders in Brisbane that he is leaving early.

It was important and necessary that all world leaders should speak bluntly about what is happening in Ukraine, and rebut Mr Putin's pretence that the well-armed separatists are nothing to do with him. But it must be questioned whether David Cameron's mocking tone on Friday night was the best way to advance the interests of the Ukrainian people. He said: "I didn't feel it necessary to bring a warship myself to keep myself safe at this G20, and I'm sure that Putin won't be in any danger." It would be better not to say that the behaviour of the Russians in staging naval exercises with a handful of ships off the Australian coast during the summit is absurd, because it is an elementary principle of negotiation that you try to give the other side a way out with dignity. Mr Cameron is not good at spurning easy laughs.

The Independent on Sunday is totally opposed to Russian aggression in Ukraine, but we have argued that it is a product of Russian weakness rather than strength. The important thing is to try to change the structure of incentives that would encourage Mr Putin to realise that it is not in his interest to get further involved in an unwinnable struggle with the majority of Ukrainians.

It was right for world leaders to speak frankly about what the Russians are doing in Ukraine, but humiliating Mr Putin is likely to be counterproductive. One of the reasons that world summits are effective is the personal chemistry: the fact that leaders meet face to face means that there is a human incentive not to offend too deeply and to seek out common ground. Mr Cameron would do well to remember that.