NATO defense ministers agreed on Thursday to set up a network of command centers in Eastern Europe and more than double the size of its rapid reaction force to better protect the region in the event of any threat from Russia.

NATO Secretary-General Jens Stoltenberg 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 defense" 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 defenses of nervous Eastern allies who were under Moscow's domination for four decades until 1989.