KIEV, Ukraine — The Ukrainian government dispatched its highest-level police and security officials to the eastern part of the country Monday in an effort to put down separatist violence described as inspired by Russia and following a script that played out in Crimea. “The plan is to destabilize the situation,” Prime Minister Arseniy Yatsenyuk told an emergency cabinet meeting Monday morning. “The plan is for foreign troops to cross the border and seize the country’s territory, which we will not allow.” On Sunday, pro-Russian demonstrations in the eastern cities of Kharkiv, Donetsk and Luhansk that had been orderly the last...