Analysis
By Jonathan Marcus BBC Defence correspondent

The US Deputy Defence Secretary Paul Wolfowitz has said that US troops may be in Afghanistan for "quite some time to come".

A global campaign against international terrorism is going to require some lengthy overseas deployments whether the Pentagon likes it or not.

This underlines that Washington has a clear stake in Afghan stability for the foreseeable future.

But Iraq too is clearly on the Bush Administration's mind.

So, could the Pentagon mount an operation against Iraq while still maintaining its commitments in Afghanistan?

'Long-term commitment'

America's founding fathers were eager to ensure that the country remained free from foreign entanglements and their advice seems to have left an indelible mark on today's Pentagon.

The US wants to remove Saddam Hussein from power

Despite having the most powerful military machine in the world, US military planners react with horror to the idea that their forces may be tied down in peacekeeping or other long-term operations in different parts of the globe.

The Pentagon likes to think that its armed forces are the tip of the military spear.

It prefers to leave nation-building to its allies.

But it is clear to all shades of US opinion that some long-term military commitment is going to be needed in Afghanistan.

While the UN-backed peacekeeping force may well have to remain in Kabul for some time, its sphere of action is limited.

It would have to call upon US commanders if its troops ran into serious trouble.

'In short supply'

A lengthy US presence in Afghanistan does not preclude though the mounting of large-scale operations elsewhere.

But US operations in Afghanistan have depended heavily upon special forces and specialised intelligence gathering systems like unmanned aerial vehicles.

Both of these assets are in short supply.

And both will be essential for any campaign against Iraq.

The Pentagon needs to get its Afghan operation just ticking over so that it can focus its attention elsewhere.

That should not be too problematic given that many key Taleban and al-Qaeda leaders are thought to have fled into the tribal areas of Pakistan.

But it is increasingly clear that a global campaign against international terrorism is going to require some lengthy overseas deployments whether the Pentagon likes it or not.

There is already discussion about what might happen if Saddam Hussein were chased from power - how long would US forces have to stay in Iraq?