Yet the leaders feel compelled to meet, and this sparks a small avalanche of comment about what kind of 'personal chemistry' is generated by these meetings. But this, too, is nonsense; take the example of what was arguably the most significant Sino-American summit - when Richard Nixon travelled to the Chinese capital to meet Mao Zedong .

Neither of these two leaders was famous for their warmth and accounts of these meetings demonstrate that they were alternately mystified and somewhat impersonal in the way they interacted with each other. Yet, at the end of the day, the United States established diplomatic relations with China and a massive raft of political and economic changes emanated from this decision. Every single thing that was agreed during this visit had been planned in advance during talks between Henry Kissinger, Zhou Enlai and their aides, who generated small mountains of paperwork to prepare for this outcome.

It mattered not one bit whether Nixon liked Mao or vice versa, nor whether the American president was happy with meals served at the banquets or delighted with his accommodation. What mattered is what matters in all bilateral exchanges of this kind: national interest.

Leaders go to summits to pursue their national interests according to an agenda set well away from the set-piece talks. If they are unhappy with any of the paraphernalia surrounding the talks, they will, in normal circumstances, shrug this off because summits are not held to determine the quality of the food or the small talk about family; this would have been almost impossible in the case of Nixon and Mao, who were notoriously bad at small talk.

Naturally, it helps if the leaders manage to hit it off as, for example, was the case with US president Ronald Reagan and British prime minister Margaret Thatcher. But the two countries were, anyway, strong allies and, even if the leaders didn't get on personally, it really would not have mattered. Nor did it matter that US president Franklin D. Roosevelt harboured considerable suspicion and some personal animosity towards the British prime minister, Winston Churchill, when it came to America's decision to join its British allies in the second world war.

Occasionally, and it really is very occasionally, some very minor amendments are made during summits which depart from the script prepared ahead of the talks, but arguably these amendments could equally have been made by an exchange of diplomatic messages. I vividly recall covering an Anglo-Chinese summit and asking one of the snotty British Foreign Office men why, as everything had been agreed in advance, he was pretending that the outcome was in question. He looked down his nose at me and said: 'Do you really think this is how summits work?' I responded by asking him to tell me how, then, they did work. I don't recall getting an answer.

The sordid truth of the matter is that, WikiLeaks permitting, practically everything that is 'achieved' at summits could be achieved by e-mail. So why do we attribute so much importance to these events?

Basically summits are elaborate public relations exercises but cannot be described as such because PR has a bad name and the grand people involved in these events do not like to think of themselves as participating in something which is little more than a glorified stunt.

However, that's what summits are. Sometimes the stunts misfire, but that's rare and is attributed to lack of preparation, as seen when Thatcher visited Beijing in 1982 to discuss, among other issues, the future of Hong Kong and was comprehensively snubbed. This won't occur in Washington this week.

Stephen Vines is a Hong Kong-based journalist and entrepreneur