Into the bully pulpit
From the briefing I'm getting, it sounds as though President Obama is going to climb into the bully pulpit and call on other nations to match the level of the United States' commitment to fighting global threats. If that is so, it may not go down that well. But speeches which are briefed as tough challenges can turn out to be emollient and friendly.
For a start, he will certainly emphasise that the approach of the Bush administration, which in turn scorned and cold-shouldered the UN, is in the past - and that the tone, the practice and the substance of American diplomacy at the UN is now different.
He'll say there has to be a multilateral approach to challenges like nuclear proliferation, peace-keeping and climate change.
This last might ring a little hollow to those who thought that contained ringing phrases and precious few promises. But the debate in the US is very different to that in the UK.
One headline in an American newspaper today reads "Obama says climate change is serious". You can't imagine any British politician getting a headline out of a statement that would be considered about as newsworthy as "sin is bad". But in the States, a recent poll indicated that 41% thought the claims about climate change were exaggerated. They could be right, but that's not my point: Obama has a more difficult battle than do European governments
He'll underline that America is committed to universal values and challenge others to show they are too. But then he will claim that America is acting aggressively to confront global challenges and will call on other countries to live up to their responsibilities.
This could partly be aimed at the two parties in the Middle East, and at the Arab world in general. But the biggest problem he faces is how to put pressure on Iran to abandon its nuclear programme, or at least the part of it he believes is designed to produce weapons.
He discussed sanctions with China's leader yesterday and put the case forcefully - but it doesn't sound as though the Chinese are ready to come on board. There is time: at least until the meeting with Iran at the beginning of October. He doesn't need results this week.
But he wants to be able to show that the new approach can bear fruit. When he starts speaking, I'll start blogging.
I’m Mark Mardell, the Ö÷²¥´óÐã's North America editor. These are my reflections on American politics, some thoughts on being a Brit living in the USA, and who knows what else? My 
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