A flag, but no UN seat for a country still lacking full sovereignty

When is a state not a state? When it's a place named Kosovo. What will be recognised today by a core of European nations and the United States is a kind of protectorate where the EU takes over the supervisory role played thus far in Kosovo by the United Nations.

The issue of recognition has exercised the minds of international lawyers for months. Kosovo will have its own flag and government, but has agreed to limitations on its own sovereignty. An EU police and justice mission will have some executive powers, and 16,000 Nato troops will remain there. It will not have a UN seat, which, admittedly, is not a necessary prerequisite for statehood.

But Britain says that when an exchange of letters takes place between the British and Kosovo foreign ministers today, it will constitute the recognition of the state of Kosovo. But other EU countries – including Bulgaria, Cyprus and Slovakia – believe just as strongly that Kosovo is not a state. They say it has been severed illegally from the rest of Serbia without the consent of Belgrade.

Both sides in the argument point to resolution 1244, the framework resolution that in 1999 set up the UN administration in Kosovo after the 11-week war that ended Slobodan Milosevic's reign of terror over the ethnic-Albanian majority in the province.

Russia argues – as it did when the Nato bombing campaign began without UN authorisation in the face of the threat of a Russian veto – that Kosovo's declaration of independence is illegal because, once again, it has been done without specific UN blessing.

However supporters of Kosovo's independence say it reflects the spirit of resolution 1244, which called for a "political solution" for the province and established an "international civilian presence" which would be maintained until the UN decided otherwise.

Countries such as the US, Britain and Germany believed that agreement with Russia, which had staunchly backed Serbia during the last two years of negotiations, was never going to be possible in a UN framework. The former Finnish president, Marti Ahtisaari, drew up an internationally approved plan calling for supervised independence. But Russia's threat to veto it at the UN prompted a final round of negotiations by a troika of US, Russian and German diplomats.

Those talks ended in failure at the end of last year with Kosovo refusing to compromise on independence, while Belgrade refused to offer more than autonomy. The Ahtisaari plan was formally endorsed by Kosovo's Prime Minister, Hashim Thaci, in his independence speech in parliament yesterday.

The second bone of contention preventing all 27 EU states from recognising Kosovo is the unilateral border change, which could serve as a precedent in other "frozen conflicts", as Russia's president, Vladimir Putin, has pointed out.

He has accused Europe of double standards for backing Kosovo's independence but not supporting independence for the Basque country and for Turkish northern Cyprus. But advocates of Kosovo's independence argue that the UN-administered Serbian province was always a special case, and that comparisons with other separatist conflicts are not valid.

Britain believes that the declaration of statehood, with international support, will provide the necessary clarity to enable Kosovo to revive its economy, ending the uncertainty over its status that kept investors away. But there are fears, even among Kosovo's supporters, that the power of the EU mission risks undermining the fledgling state, rather than reinforcing it.