By the BBC's Rob Watson in Washington

When the United Nations development summit opens in the Mexican city of Monterey on Monday, many will be looking to see what pledges the United States is willing to make.

The conference is trying to arrange the financing which will pay for the Millennium development goals agreed by the UN two years ago.

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But the US has always been regarded as the bad boy of development aid.

Consider for a minute the figures.

The United States gives some $11bn a year in aid to the world's poorest nations.

It may sound like a lot, but not when you consider it's only about 0.1% of America's GDP.

It also compares badly with the world's other rich nations which tend to give around 0.3% of their economic output in aid.

New policy

Indeed, the US in general and the Bush administration in particular has always sounded decidely sceptical about the whole concept of rich nations giving to poor.

US Treasury Secretary Paul O'Neill noted recently that the world had "precious little" to show from four decades of aid.

The US is willing to give aid, if countries measure up

That's why President George W Bush was expected to be something of a target in Monterrey for those who believe the US does not do enough to help the world's poor.

I say "was" because President Bush has now announced a major shift in US aid policy in something of a pre-emptive strike at potential Monterrey critics.

< Speaking in Washington just days before leaving for Mexico the president not only reaffirmed the usefulness of foreign aid, but promised an extra $5bn of it, a 15% increase on exisiting totals.

But it won't be given to just anyone.

Three tests

In an effort to end what might be called the wide perception of aid money ending up lining the pockets of Third World dictators, the president laid down some conditions.

He said it would only go to countries that live by three broad standards - "ruling justly, investing in their people, and encouraging economic freedom".

And this in essence is the message President Bush and his army of officials and diplomats will be taking to Monterrey.

Methods not figures

The message is that the US is prepared to give more money but that there has to be good government in return from the developing world.

That general principle is already enshrined to some extent in the pre-agreed UN document government leaders will rubber-stamp in Moneterrey, which urges the rich nations to give more and the poor nations to do better with the money they get.

So will Monterrey be all about how much money?

Not if the US can help it.

American officials say the debate needs to be less about how much aid is given and more about how to use it.