Why Ukrainian forces gave up Crimea without a fight - and NATO is alert

FILE PHOTO: Ukrainian acting President Oleksander Turchinov (L) and acting Defence Minister Mykhailo Koval visit a military exhibition near the settlement of Desna in Chernigov region, Ukraine April 2, 2014. Mykhailo Markiv/Ukrainian Presidential Press Service/Handout/File Photo via REUTERS

KIEV/SEVASTOPOL, Crimea (Reuters) - The career of Sergei Yeliseyev helps to explain why Ukraine's armed forces gave up Crimea almost without a fight - and why NATO now says it is alert to Russian attempts to undermine military loyalty in its eastern European members.

His rise to become number two in the Ukrainian navy long before Russia seized Crimea illustrates the divided loyalties that some personnel in countries that once belonged to the Soviet Union might still face.