A crisis in foreign affairs is looming, which could turn out to be one of the worst the Blair government has faced since it came into office. I am talking about Zimbabwe and the twilight days of Robert Mugabe's appalling government. Maybe I am being optimistic in referring to the "twilight" of the man who has ruled Zimbabwe since independence. But I have a strong sense that the Zanu PF government in its present guise will not last the year.
Later this month, the people of Zimbabwe will, in theory, have the chance to vote Mr Mugabe out of office; few believe that the election will be allowed to proceed peacefully if it looks as if the anti-Mugabe vote in the referendum on constitutional change is about to be repeated.
Mugabe is a man full of hubris and, like many a megalomaniac before him, he has sought to conflate his persona and the nation. The leader who is the nation cannot possibly harm the nation. So the warped, self-obsessed psychology of this little-league despot would have his people believe. The striking thing is that the developed world has taken so long to cotton on to Mr Mugabe's ambivalent attitude to the democratic process. For a long time he was a darling of the left and feted in the international aid community. The less pleasant aspects of his rule tended to be overlooked as foreign donors poured cash into Zimbabwe.
The fact is that he was never a nice man. He showed his true colours back in 1983 when he sent the North Korean-trained 5th Brigade into Matabeleland to suppress his tribal opponents. The result was a campaign of mass murder and torture of civilians against which the activities of the previous Rhodesian forces looked positively moderate.
But we overlooked all of that. There were bigger things to feel pious about. Down south, in the apartheid republic, the blundering Boer, PW Botha, was busy providing the West with a big fat target for its moral outrage. The behaviour of Mr Mugabe's security forces was regarded as Zimbabwe's own business. In fact, Robert Mugabe was an honoured guest at Commonwealth conferences, where he led the charge against apartheid South Africa. We are paying for that now. Having gotten away with murder in the past, the government in Harare will see no reason why it cannot do so again. A report by the human-rights group Africa Rights points out that some Zanu toughs have been going to villages in Matabeleland and warning people that the 5th Brigade will be back if they do not support the party.
In considering his ruthless playing of the race card against white farmers, it is worth remembering which group he backed in the South African struggle. Nelson Mandela's ANC was regarded as far too wishy-washy and liberal for Mugabe. Instead, he backed the Pan- Africanist Congress, whose military wing killed with the slogan: "One settler, one bullet." The PAC fought a racist war. It was avowedly anti-white, and that undoubtedly appealed more to Mr Mugabe than Mandela's talk of reconciliation and nation-building.
The British government has responded to the escalating crisis in its former colony by deploying a verbal gunboat in the form of Peter Hain, the Foreign Office minister. A former anti-apartheid campaigner, Mr Hain has aroused the ire of Mugabe and his henchmen by criticising the regime for opening British diplomatic freight and by announcing that the Government had contingency plans to evacuate British citizens - white Zimbabweans - in the event of a breakdown of security. Peter Hain is a passionate and committed Africanist. He is also a very genuine human being. But for him to go public on the contingency planning was a mistake; it could help to sow panic and increase Mugabe's paranoia about British intentions.
It also may have raised unrealistic expectations about Britain's intentions and capacity to intervene in the crisis. If there is a military coup, if a civil war erupts between pro- and anti-Mugabe factions, what then? Is Britain going to send troops to quell the disturbances? Of course not. White soldiers are not going to be sent running around the Zimbabwean bush to be shot to pieces in the middle of a civil war. And short of throwing Mugabe out of the Commonwealth - a move the Government is holding up its sleeve - there is little in the way of practical pressure that it can exert. The real international player in this game is not Britain. It is South Africa.
Robert Mugabe enjoys baiting the British. He can do it because London can do little to harm him. But Thabo Mbeki is a very different case. With a flick of the switch, the South Africans could remove Zimbabwe's electricity supply. The country's economy is hugely dependent on South Africa, with many impoverished Zimbabweans seeking work south of the Limpopo. And when it comes to military power, the only army on the continent capable of frightening Mr Mugabe on his home turf is the South African National Defence Force.
The South Africans are feeling noticeably bolder about foreign policy, and are asserting their primacy as the regional superpower. The disastrous intervention in Lesotho has slipped into distant memory, and under Thabo Mbeki there are signs of a more coherent approach to foreign-policy challenges such as Zimbabwe, the Angolan war and the war in the Democratic Republic of Congo.
If Zimbabwe does erupt into serious conflict, the refugees will head south in their hundreds of thousands. South Africa has enough on its plate without a huge influx of hungry and homeless Zimbabweans. Mbeki has already been to Harare to spell out the realities to the Zimbabwean leader. So far he has been reasonably polite, but there is no ambiguity about what South Africa wants: Mugabe must stand down now. Follow the examples of Nelson Mandela and Kenneth Kaunda and retire. The problem for Mugabe now is that he is so despised by his people that a peaceful retirement would be impossible within Zimbabwe's borders.
If Zimbabwe's leader does go quietly, the vast edifice of repression and the culture of cronyism that grew up around him will collapse. The new policemen will come knocking on the door sooner rather than later. The man who gave refuge to one of Africa's most bloody tyrants - Mengistu of Ethiopia - Mugabe may find himself looking for a hiding-place in the near future.
There are a number of possibilities. His old friend Sam Nujoma in Namibia might offer a haven, or maybe Botswana or Angola. But I fear that he may be too full of hubris for that, and that he will bring himself and his country crashing down in flames. The only hope is for Thabo Mbeki to keep increasing the pressure. He can start by insisting on international monitoring - led by Africans - of the forthcoming elections, and follow up by promising to intervene by whatever means necessary in the event of a military coup or wide-scale disruption of the democratic process. All of that goes to the heart of the great promise South Africa presented to the world in 1994: Africa does not have to be a place where change only comes through the barrel of a gun. This is Mr Mbeki's chance to prove his commitment to that principle.
The writer is a BBC Special Correspondent