SIMFEROPOPL, UKRAINE - MARCH 12:  Armed men believed to be Russian military patrol outside a Ukrainian military base on March 12, 2014 in Simferopol, Ukraine. As the standoff between the Russian military and Ukrainian forces continues in Ukraine's Crimean peninsula, world leaders are pushing for a diplomatic solution to the escalating situation. Crimean citizens will vote in a referendum on 16 March on whether to become part of the Russian federation.  (Photo by Dan Kitwood/Getty Images)