Tony Blair mentioned Kosovo in a sub-clause of his exit speech yesterday, coupled with Sierra Leone. He was glad that in both cases he had “made our country one that intervened”, and moved on to Iraq, which he pronounced “bitterly controversial”.

Kosovo is still controversial. The solution towards which the United Nations Security Council is edging is enormously risky even though it is the best available: encouraging the disputed province to declare independence from Serbia in the hope that the UN will then acknowledge its sovereignty.

Most of Britain’s fears, as its diplomats try to shepherd this plan through the council, have focused on Russia. On its own it could scupper the plan, and it may do so, out of old allegiance with Serbia, which claims sovereignty over the Albanian-majority province. Will Russia veto the plan in the council? Will awareness of its support fan violent resistance on the ground the minute that Kosovo expresses independence? Will the 100,000 Serbs in Kosovo be killed or flee?

It is perfectly reasonable, with the 78 days of war in 1999 still so fresh, that these practical questions dominate efforts. But the questions of principle that South Africa, as a temporary member of the council, has raised are more troubling. It is afraid that independence for Kosovo would set a precedent for wiping out old state boundaries in favour of tribal divisions. It is right that this is an ugly answer to sectarian rifts – ask Iraq.

Sir Emyr Jones Parry, the British Ambassador to the UN, expressed some confidence this week that the Security Council would manage to vote later this month on a Kosovo resolution. The resolution would mark an end to UNMIK, the UN mission; it would authorise a continued European Union presence; and it would, in Jones Parry’s understated phrase, “have to say something on Ahtisaari”.

That is the core of the problem: reaching agreement on the plans drawn up by Martti Ahtisaari, the EU’s special envoy to Kosovo, through which the province could declare independence from Serbia. “I would like it to endorse Ahtisaari,” said Jones Parry, although he pointed out that even if the Security Council did so, that would not mean it was overtly encouraging independence.

Kosovo would still have to declare independence, and then hope that this was backed by the UN: nine votes and no abstentions from the 15-member Security Council, and two thirds of the General Assembly.

Russia is the shadow looming over this. Its relations with Europe are poor, with the US even worse, and it may choose to block this because it can, with no cost to itself. But the surprise in the diplomatic calculations has been South Africa, a vocal member of the council first on Iran, now Kosovo.

Its objections may be too abstract to have much purchase on the Kosovo row, but it has a point. Splitting nations up – however historically debatable their borders – because different ethnic groups decide it is intolerable to share a nationality is an unsettling precedent.

In Kosovo’s case it offers no reassurance about the future of the tenth of the population that is Serb and living in enclaves, surrounded by ethnic Albanians with vivid memories of recent hostilities.

“Kosovo was never about creating a state,” says Jones Parry. “It was about taking the Serb oppression out.” But the solutions are turning out to look the same.

Iraq also appears torn between two repellent futures: one of ethnic separation, with thousands killed on the way, or one where the majority offers the minority few rights.

Tony Blair may have acknowledged Iraq as a controversy; he was wrong to breeze past Kosovo, putting a tick in the box for achievement. It is Northern Ireland that is his best claim to have brokered peace between warring communities. Kosovo is not close.

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