There is something ruthlessly systematic about the American campaign in and around Afghanistan.

It's not so much the military operation, which has yet to face a real test. It's the diplomacy, which is beginning to look like a well paced marathon run.

It was last Friday - five days after the start of the bombing campaign - that Washington announced the last key element in Afghanistan's military encirclement.

Uzbekistan joined Pakistan and Tajikistan in allowing American combat forces to be stationed on its soil.

Now the United States is already looking closely at the future shape of an Afghan government if and when the Taleban regime collapses.

It will be the main topic of discussion in talks being held in India and Pakistan by the US Secretary of State, Colin Powell.

Officially the Americans do not want to be seen assembling what could get a reputation as a puppet government in Afghanistan.

In practice, the issue is racing to the top of the agenda. Washington's fear is that a Taleban collapse could produce an even more anarchic situation in the country.

New government

One Indian official just smiled when asked if the Americans were involved in building a new government. "The Afghans have to put the government together themselves," he said, "but there will have to be a lot of hand-holding and toes to the fire."

Mr Powell will probably repeat, in India and Pakistan, what's become a mantra in Washington.

The US wants the next government to be "broad based and representative of all Afghans", he will say. Beneath that bland statement lies a web of intrigue.

Two ideas dominate the Afghan political landscape. First there is the involvement of the former king, Mohammad Zahir Shah.

Exiled since 1973, he has been receiving an increasing stream of visitors at his mansion in Rome. He could be a unifying figure if he does not overplay his hand.

The other element is the convening of a "loya jirga" or grand council. Under this plan, hundreds of Afghan tribal and factional chiefs would assemble, following a custom thousands of years old, in order to re-order their government.

The problem, put quite simply, is to stop them plotting to kill each other.

Fresh start

Then there is the part to be played by Afghanistan's neighbours. Here is where Mr Powell's trip could be crucial.

Pakistan needs to be reassured that a sympathetic government would replace the Taleban it helped to install.

India - and the rest of the world - need to know that there is not to be a repeat of the disasterous experiences of the last few years.

All of these ideas need to be assembled, while Mr Powell reassures the Indian and Pakistani governments of their role in his grand coalition.

He will also have to talk to them both about keeping the temperature down in Kashmir.

Meanwhile on the streets of Pakistan, his arrival is being marked by a general strike - called in protest by Islamic religious parties.

It could well be his most challenging diplomatic mission to date.