Nato defence ministers yesterday agreed to set up a network of command centres in eastern Europe and more than double the size of its rapid reaction force to betterprotect the region in the event of any threat from Russia.

Nato Secretary-General Jens Stolten-berg said the measures, part of the alliance’s response to Russia’s annexation of Ukraine’s Crimea, amounted to “the biggest reinforcement of our collective defence” since the end of the Cold War 25 years ago.

With East-West tensions running at their highest since the Cold War era, Nato has made clear it will not intervene in Ukraine but will bolster the defences of nervous eastern allies who were under Moscow’s domination for four decades until 1989.

Ministers agreed to more than double the size of Nato’s existing rapid reaction force to 30,000 soldiers from 13,000, led by a 5,000-strong “spearhead” force, part of which will be ready to move within 48 hours, according to Stoltenberg.

Britain, France, Germany, Italy, Poland and Spain will take turns in commanding the spearhead force, Stoltenberg said.

The alliance will establish a new northeastern regional headquarters in Poland and a smaller southeastern headquarters in Romania.

Six command centres, staffed by national and Nato officers, will be set up in Poland, Romania, Bulgaria and the three Baltic states to plan exercises and organise reinforcements for those countries in an emergency.

“The Russians should get the message that we and other countries have been delivering to them – that they should back off from their aggression against Ukraine,” Canadian Defence Minister Rob Nicholson told Canada-based reporters by phone from Brussels.

The plan, which builds on decisions taken at Nato’s summit in Wales last September, falls short of the hopes of some eastern European countries for Nato to set up large bases in the region, but it raised concern in Russia.

Ministers also discussed growing concerns within NATO about Russia’s nuclear strategy and indications that Russian military planners may be lowering the threshold for using atomic weapons in any conflict, diplomats said.