Estimated 6,600 U.S. citizens were living in Ukraine in October -State Dept

A U.S. government estimate in October found there were 6,600 U.S. citizens residing in Ukraine, State Department spokesperson Ned Price told reporters on Monday, amid fears over a Russian buildup of troops and military equipment near Russia's border with the former Soviet republic.

Another 16,000 tourists and visitors could be in Ukraine at any one time, according to the October estimate, but the number there now is likely far lower given the warnings over a potential Russian invasion of Ukraine, Price said.