By Jonathan Marcus
BBC diplomatic correspondent
For now there is not going to be a Polish solution to Nato's problems in Afghanistan.
Nato spokesmen are making it clear that Poland's decision to send 1,000 troops to the country early next year - a few months earlier than planned - has nothing to do with the alliance's current military problems in the south of the country.
The ferocity of the combat in Afghanistan surprised some Nato officers
Nato is still struggling to find up to 2,500 extra troops for southern Afghanistan and it needs them urgently.
If they cannot be found then the success of Nato's mission could be called into question and this in turn could have a considerable impact upon future perceptions of the alliance itself.
Nato leaders accept that Afghanistan represents a fundamental test for the alliance.
The crucial problem for any international institution is relevance. Is it still useful to its members? Can it re-invent itself for a world that is very different from that in which it was founded?
Into the unknown
So far Nato has not done too badly. In the wake of the ending of the Cold War, Nato lost an enemy but it soon found a new role in exporting stability.
In part, this was a diplomatic process by broadening its membership eastwards to take in not just former Warsaw Pact members like Poland, but also countries like the Baltic republics whose territory was once part of the Soviet Union itself.
But Nato also became a key international military player - perhaps the only organisation in the world capable of mounting major peace support missions in Bosnia and Kosovo.
However Afghanistan presents very different challenges.
This is Nato's first ground operation outside Europe and in southern Afghanistan, a mission that was initially framed as a peace-keeping operation has turned into full-scale combat.
Nato troops are holding their own - indeed, they claim to be inflicting serious casualties on the Taleban insurgents.
But they cannot fight, control territory and provide development assistance at the same time.
What is needed above all is a well-armed mobile reserve capable of moving swiftly to engage concentrations of Taleban fighters.
Nato's top military commander and its top civilian official have both strongly backed the call for additional troops.
They are needed now before the winter weather sets in and the Taleban re-groups for a new campaigning season in the spring.
The reluctance of Nato governments to find the necessary soldiers raises all sorts of questions about the alliance's ability to mount this kind of operation.
Mission too far?
Nato is not going to wither away.
It still plays an important role in the Balkans and in helping to integrate the countries of the former eastern bloc.
But the times are changing.
Nato is the major trans-Atlantic forum and it has inevitably suffered from the broader strains between many European countries and the Bush administration.
The "war on terror" has left many of its members uncomfortable.
They do not entirely share Washington's world view. And the Bush administration has tended to reinforce key bilateral relationships rather than bolstering Nato as a whole.
It is far too early, though, to write Nato's obituary.
A resurgent Russia, new challenges from across the Mediterranean, a new US administration and new leaders in key alliance members like the UK and France could help to move Nato back to the centre-stage of diplomacy.
But in the end an organisation has to be judged by what it can do.
From the start, alliance commanders in Afghanistan have never been given the forces that they requested for the job.
Now they cannot secure timely reinforcements when soldiers are losing their lives.
There is a growing danger that Afghanistan will be seen as a mission too far.