Pro-Russian protestors have taken over government building's in three big cities in the East of Ukraine.
This includes the city of Donetsk, where demonstrators want to break away from Ukraine and are calling for a vote next month.
A few weeks ago, neighbouring country Russia took over Ukraine's southern region of Crimea.
Ukraine is a country split over whether to have closer ties to Russia, or to the European Union.
It has been in crisis over recent months, with tensions mounting between people who want Ukraine to stay an independent country, and those who think it should become part of Russia.
Ukraine is sending security officials to the Eastern cities affected - Donetsk, Luhansk and Kharkiv - to try and regain control.