Will Kosovo be first proxy military confrontation with neo-Soviet Russia?

British conservative leader David Cameron will sound the alarm of instability in the Balkans, possibly precipitated by Russian opposition to an anticipated declaration of independence from Serbia by Kosovo.

Speaking in Washington, the Conservative leader will issue a stark warning that Russia's increasingly assertive foreign policy is jeopardising Britain's national security.

Mr Cameron fears a diplomatic and military crisis could arise over Kosovo, the province of Serbia which has effectively been a United Nations protectorate since Nato invaded to stop ethnic cleansing by Serb forces in 1999.

The ethnic Albanian government of Kosovo is threatening to declare independence from Serbia on Dec 10. Moscow is backing Serbian attempts to block the declaration, while the United States and the European Union are in favour.

"Let me make it clear: there could be a new crisis in the Balkans by Christmas," Mr Cameron will say in a speech to the Brookings Institution, a Washington think-tank.

If Kosovo does declare its independence on 12/10, the reaction from Vladimir Putin will have to be watched closely, as it could be a bellwether for future Russian activity in eastern and central Europe.