Spain, Romania and Cyprus will join Serbia and Russia in giving anti-Kosovo depositions during hearings from 1 to 11 December at the UN´s top legal body, the International Court of Justice in The Hague.
The legal challenge - on the "Accordance with International Law of the Unilateral Declaration of Independence by the Provisional Institutions of Self-Government of Kosovo" - was brought by Serbia, which continues to fight against the secession of its former province.
An EU report out this week criticised Serbia for creating "parallel structures" and sponsoring by-elections in Serb-controlled parts of Kosovo in attempts to undermine Pristina´s authority.
Spain, Romania and Cyprus together with Slovakia and Greece declined to recognise Kosovo´s independence last year. But the group of three´s involvement in The Hague procedure marks a shift from passive to active resistance against Kosovo statehood.
With Germany, France, the UK, the Netherlands and the US set to make pro-Kosovo statements at the UN hearings, the verdict, which is expected in early 2010, could go either way.
The ruling is in any case to have a purely "advisory" force. It will not influence in a technical sense Kosovo´s bid to get a seat in the United Nations. But it will give political ammunition to either Pristina or Belgrade in an ongoing confrontation in a still hot part of Europe.
"A positive opinion would have a huge positive impact on the unfortunately still fragile stability of our region," Kosovo parliament speaker Jakup Krasniqi told EUobserver. "It would also support those nations that would one day like to see Kosovo become a full member of the wonderful family called the European Union."
EU institutions are unwilling to criticise Spain, Romania or Cyprus´ involvement in the UN case.
EU foreign relations chief Javier Solana is one of the main architects of Kosovo´s independence. But the question touches on sensitive areas of national interest, such as Spain´s handling of Basque separatists or Cyprus´ relations with the Turkish-controlled part of the island.
"It´s not an EU competence in any way. The important thing is that there is unity inside the EU on moving forward with practical matters, such as the EU´s rule of law mission in Kosovo," one of Mr Solana´s officials said.
Facts on the ground
The idea that Serbia or Russia can at this stage roll back Kosovo´s statehood is anathema to the EU.
"The states of the International Steering Group have said that they see Kosovo´s independence as irreversible. So I don´t think, realistically, that things can go backwards for Kosovo," Andy McGuffie, a spokesman for the ICO, the steering group´s Kosovo-based office, told this website.
The International Steering Group is a club of 25 countries formed in February 2008 to help put Kosovo on its feet. The roll-call of members includes 20 EU states plus Croatia, Norway, Switzerland, Turkey and the US.
The EU has since the birth of Kosovo argued that its statehood is a unique "sui generis" case which cannot be used as a model for other breakaway entities.
But the cost of its support for Kosovo can be seen in Georgia, where Russia has applied similar arguments of facts on the ground to try to establish separatist forces in the Abkhazia and South Ossetia regions as independent countries.
To date recognised by Russia, Nicaragua and Venezuela only, the Abkhaz and South Ossetian cause is beginning to get a foothold in the US establishment.
In an editorial decision that would have been hard to imagine one year ago, leading US newspaper The Washington Post on Friday (16 October) published an op-ed by Abkhaz leader Sergei Bagapsh which referred to him as "President" in a statement entitled "Abkhazia will succeed."