By Jon Leyne BBC correspondent at the US State Department

In an interview with the newspaper USA Today, US Defence Secretary Donald Rumsfeld continued the administration's policy of trying to move the spotlight off Osama bin Laden.

But, not for the first time, the defence secretary seems to have wandered off his script, when he was pressed on whether he was confident Bin Laden would be captured or killed:

"Well, it is a very difficult thing to do," he said. "It's a big world. There are a lot of countries. He's got a lot of money, he's got a lot of people who support him, and I just don't know whether we'll be successful."

It was a long way from President Bush rhetoric about "smoking out" the "evil-doers".

A few hours after the article appeared, Mr Rumsfeld clearly backtracked. "I think we are going to get him (Bin Laden)," he told the daily Pentagon briefing.

Tripping over words

It is confusion more about language than about policy.

The US has begun urging the Northern Alliance forward

There is no doubt capturing or killing Bin Laden remains a key war aim. But Washington does not want the success or failure of its war against terrorism to be judged by the hunt for Bin Laden. And there's no arguing that the United States has wider war aims.

In Afghanistan itself, the Bush administration has been trying to coordinate its military strategy with planning for the future of the country.

For a time, American bombers held off from targeting Taleban positions on the front line with the rebel Northern Alliance.

The fear at that stage was that a rapid Taleban collapse could plunge Afghanistan into even worse chaos.

Future government

Now, following Secretary of State Colin Powell's visit to the region, work by the United Nations and meetings among Afghan exiles, the outlines of a possible future government have begun to take shape.

The Americans have begun targeting Taleban battle lines, and almost openly urging the Northern Alliance to push forward.

US military planners have been surprised by the Taleban's tenacity

"I think it would be in our interest and the interest of the coalition to see this matter resolved before winter strikes," said Colin Powell at the weekend.

The fears about a sudden collapse of the Taleban have been replaced with a degree of frustration about the regime's survival. At the Pentagon briefing on Wednesday, Rear Admiral John "Boomer" Stufflebeem described the Taleban as "tough warriors".

"I am a bit surprised at how doggedly they're hanging on to their - to power," he said.

So in a matter of days the pendulum has swung from fear of too much progress, to fear of too little.

Washington has work to do refining its military strategy and trying to avoid sending more mixed messages in the information war.