Yesterday's barracking of Colin Powell by delegates and activists at the Earth Summit was unprecedented.
In almost 30 years of covering international conferences I cannot remember any reception that came close – no matter how notorious the speaker.
Even Margaret Beckett, Britain's chief negotiator, said it showed how "angry" delegates were with America. She added: "I understand how delegates feel", before going on to condemn the "abuse".
But it was more than just anger. It was the release of fury and frustration that has been building up throughout the summit. Indeed it has been brewing ever since President George Bush set out to destroy the Kyoto Protocol on global warming, shortly after attaining power.
It is a strange reversal. For decades America led in pressing for international environmental action – under Republican and Democrat administrations. Under President Nixon, of all people, it took a leading role at the first Earth Summit, in Stockholm in 1972. Under President Reagan it led the successful international drive to phase out chemicals that destroy the ozone layer.
Mr Bush's own father attended the Earth Summit in Rio and delivered a speech accepting the need for action and promising to take it.
Maurice Strong, who led both the Stockholm and the Rio summits, told the US Senate six weeks ago of "the recent retreat by the United States from its longstanding role as the leading driver of these issues". And he warned that when the US acts unilaterally "it inevitably pays a cost in terms of the resentment and reluctance of others to co-operate on other issues of importance to the United States" – and that a "new configuration of leadership" was beginning to emerge.
Some of that leadership is coming from the European Union, which often took the most progressive position here. Some is coming from Third World nations such as Brazil – which launched an initiative to quadruple within a decade the proportion of energy the world gets from clean renewable sources – and South Africa, which ran the summit efficiently and with aplomb. Indeed, South Africa's Foreign Minister, Nkosazana Dlamini-Zuma, pointedly commented, as the summit opened without George Bush in attendance, that political will did not depend on one man.
The first fruits of that leadership also became clear at the summit. When Mr Bush declared the Kyoto Protocol "dead", the rest of the world successfully completed the negotiations without him.
The treaty is now likely to take effect within months. Once it does, American business is likely to press Mr Bush to join, so that it does not miss the opportunities the protocol presents for making money.
That, rather than the barracking of General Powell, is the kind of pressure he understands. He may be forced to give way – and, if he is, he will suffer a far greater humiliation than his Secretary of State did yesterday.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies