By Pavel Polityuk and Maria Tsvetkova KYIV (Reuters) – Ukraine will introduce a nationwide state of emergency in which special restrictions will apply in order to keep the country calm and protect its economy amid fears of a Russian invasion, a senior Ukrainian security official said on Wednesday. The state of emergency will last for 30 days and can be extended for another 30 days, Oleksiy Danilov told a briefing. Parliament must now vote to enact the decision. Introducing a state of emergency gives powers to the authorities, who can choose which ones to implement. These could include restrict…