Tensions are at an all time high in the Ukrainian region of Crimea on the day of a referendum to decide whether to rejoin Russia.<br/> <br />Here in the Crimean capital a group of armed policemen burst into a hotel, where many international correspondents have been staying.<br/> <br />Some police officers say it was a planned drill, while Ukrainian officials say it was in reaction to a false tip off.<br/> <br />Here outside Simeropol, though, it's no drill…troops -- presumed to be Russian - are deployed to reinforce a Ukrainian military base.<br/> <br />It's part of a major buildup of Russian military across Crimea.<br/> <br />Pro-Russian forces seized this area when Moscow-backed president Viktor Yanukovich was ousted in February after months of protests.<br/> <br />But now Kiev says Russian paratroopers have crossed the Crimean border and seized a village in mainland Ukrain.<br/> <br />(SOUNDBITE) (English) YURIY SERGEYEV, UKRAINIAN AMBASSADOR TO THE U.N., SAYING:<br/> <br />" This is something which is changing the situat
