Leading article: A military challenge to Mr Mugabe

Is the alliance of forces that has kept Robert Mugabe in power finally starting to crack? For more than a decade now Zimbabweans have watched their once-prosperous country slide into penury and decay. Their government's mismanagement has brought hunger, disease, plunging life-expectancy, joblessness and hyperinflation to a land that was at one time the breadbasket of Africa. As the months and years have passed, and Mr Mugabe secured his power by fair means or foul, one could only marvel at people's forbearance. Every forecast that Zimbabwe could survive not a moment longer was disproved, as people somehow found a way.

It was simply impossible to dislodge Mr Mugabe – and so long as he was there any change was out of the question. The lengths to which he went to cling to power after elections this year in which he and his Zanu-PF party were patently beaten showed what Zimbabweans were up against. The government was finally forced to surrender its majority in parliament, but Mr Mugabe himself hung on, eventually negotiating a power-sharing deal with the opposition Movement for Democratic Change, every clause of which he subsequently evaded.

One reason, perhaps the only reason, why Mr Mugabe was able to flout the judgement of his people for so long was the alliance he had sealed with the military and the veterans – his former comrades-in-arms against the white minority regime of Ian Smith. Now, it seems, that alliance may be dissolving. Police used tear gas to disperse dozens of soldiers running riot through Harare, smashing shop windows, looting and shouting "Enough is enough". The protest represented an unprecedented breakdown of the hitherto united front between the Zanu leadership and the military.

With a cholera epidemic raging and much of Harare without water, it is hard to see how much longer Mr Mugabe's power can endure. This time last year, such a prospect might have been resisted as leaving a dangerous power vacuum. Now that there is a legitimately elected leader waiting in the wings, and a less cautious President in neighbouring South Africa, that danger is past. Mr Mugabe's departure is long overdue.