Ukraine's military appears to be stepping up its efforts to bring eastern and southern Ukraine back under government control.
Ukrainian troops today have been fighting gun battles with a pro-Russia militia occupying the eastern city of Slovyansk. The country's interior ministry says four officers have been killed and 30 others wounded in those clashes.
A statement on the ministry's website on Monday did not give further details about how those officers died. But a separate statement said Ukrainian troops had started an "anti-terrorist operation" Monday morning against the pro-Russia forces, which numbered around 800.
Slovyansk has been the heart of an uprising in east Ukraine against the central government in Kiev, which came to power after the country's Russia-leaning president fled following months of street protests.
Meanwhile, the government has sent an elite national guard unit to re-establish control in the southern port city of Odessa
Pro-Russian activists there vowed to take city buildings after attending the funeral of a politician who died in a fire that killed over 40 people last week.
Former U.S. ambassador to Ukraine, Steven Pifer, discusses the situation in East Ukraine with Here & Now's Meghna Chakrabarti.
This segment aired on May 5, 2014.