Russia is no longer a threat  Russia no longer presents a credible threat to Eastern Europe or the existing NATO States which NATO expansion could counterbalance. Russia can no longer offer the conventional military threat of the Cold War. The acceptance of this reality by the US is evidenced by the fact that troop numbers in Europe are much reduced from a peak of 277,000 troops and will be reduced further to 30,000 in the next few years. [1] This is the key question for a military alliance as defence is the key purpose. Expansion should therefore be decided based upon the yardstick of whether the expansion is necessary for the security of NATO members. If there is no credible threat then there is no reason to expand the alliance. At the same time while Russia is no longer a conventional military threat it still has its immense nuclear armament. This will remain a threat no matter how many of Russia’s neighbours join NATO but Russia could feel increasingly obliged to focus on its nuclear arsenal to respond to NATO expansion – something which would create a threat to western Europe.  [1] Shanker, Thom, and Erlanger, Steven, ‘U.S. Faces New Challenge of Fewer Troops in Europe’, The New York Times, 13 January 2012,