It is a rare Gordon Brown speech that does not set five tests for someone. Yesterday he set five tests for Afghanistan: better security, good governance, inclusive politics, economic development and regional partnerships. The five tests were his response to the four charges that have been levelled, not least by this newspaper, against the Prime Minister’s Afghanistan policy.

First, he has been unable to find the words of reassurance that, as the body bags arrive home, are needed by an increasingly sceptical British people. Second, he has not expounded a clear strategy or detailed the options available. Third, he has failed to acknowledge the blatant corruption of the Karzai regime. Fourth, he has not given the war in Afghanistan the forensic attention that he applied to the economy.

Though the Prime Minister’s address at the Royal College of Defence Studies left a lot unsaid, it did at least take these charges head-on. His articulation of the continuing case for British involvement in Afghanistan was resilient and coherent. He reiterated that much of the violence seen on the streets of New York, Bali, Baghdad, Madrid, Mumbai, Rawalpindi and London began in the regions of the Pakistan-Afghan border. He also took on the credible case, voiced by Kim Howells this week, that the war would be better fought on the streets of Britain. The Prime Minister made the much needed point that the war is not waged in either London or Kabul — it is waged in both places at once.

Britain is, of course, the junior partner in this endeavour. Mr Brown hinted at this but was too courteous to point out what is obvious — that no clear strategy can emerge as long as President Obama delays the decision on whether to send the 40,000 troops requested by his generals.

Mr Brown’s admission that the Afghan Government has become “a byword for corruption” was both candid and true. It was also overdue. Finally, though, he appeared to put the Karzai regime on notice, saying that he is not prepared to risk the lives of British soldiers in defence of a corrupt Government. This sounded like an ultimatum, a decisive “or else” moment. But it is not clear how that sits with the equally clear statement that “we cannot, will not and must not walk away”. If President Karzai reneges on his promise to rid his administration of corrupt friends, what does Mr Brown propose to do?

He said emphatically that the Afghan leader would forfeit the right to international support if he did not meet the five tests for a successful Afghan Government. It may be that Mr Brown is suggesting that his support could shift to another putative leader or that aid resources might be diverted from central to local government. The West needs to be clearer on this sanction as it needs to be clearer about the alternative to Karzai. If it is not be a Western-style democracy, then it should at least encompass an Afghan solution, such as a loya jirga.

Mr Brown’s summary of the most desirable outcome was clear and right — that well-trained Afghan forces take responsibility as soon as possible, that the pressure on all extremist and terrorist groups should be maintained and that, in due course, a safer Britain will be the result. It now remains to be seen whether Mr Brown does apply himself, with the Stakhanovite fervour of which he is clearly capable, to making it happen.