Four Ukrainian soldiers were killed and 30 injured during a gunfight in the eastern city of Sloviansk today, according to Interior Minister Arsen Avakov, as the government sent an elite national guard unit to attempt to regain control of Odessa. 

According to the Associated Press, pro-Russian separatists and Ukrainian troops have been exchanging steady fire in and around Sloviansk today: 

Associated Press reporters heard gunfire and multiple explosions Monday in and around Slovyansk, a city of 125,000 that has become the focus of the armed insurgency against the new interim government in Kiev. Interior Minister Arsen Avakov said on his agency's website that pro-Russia forces numbering about 800 were deploying large-caliber weapons and mortars.... Both sides indicated fighting was taking place at several sites around the city. 

Several outlets are also reporting that a Ukrainian helicopter has been shot down: 

Ukrainian officials have been trying to regain control of Sloviansk for some time now, since pro-Russia separatists have occupied government buildings and called for the city to be annexed to Russia, like Crimea. But the strategic and culturally significant port city of Odessa was largely untouched by violence until last week, when a seized government building caught fire during a protest, killing dozens. Now, with Odessa on the line and Crimea effectively the property of Russia, Ukraine fears that it could lose access to the Black Sea altogether. Reuters reports

The violence in Odessa, a southwestern port with a broad ethnic mix from Russians and Ukrainians to Georgians and Tatars, was seen as a turning point in Kiev, encroaching for the first time into an area beyond the Russian-speaking east.

Luhansk, eastern Ukraine. REUTERS/Vasily Fedosenko 

And Ukrainian officials fear that police in the region sided with the separatists. Again, Reuters notes

"The police in Odessa acted outrageously, possibly in a criminal fashion," Avakov wrote on his Facebook page. "The 'honor of the uniform' will offer no cover." Ukrainian leaders have made it clear they see the police force across wide areas of the country as unreliable in the face of rebellion they say is backed by Moscow and led on the ground by Russian special forces. The units Avakov referred to emerged partly from the uprising against Yanukovich early this year.

Meanwhile, a new threat is emerging in the region, according to Barnard College and Columbia University political scientist Kimberly Marten, who writes in the Washington Post that officials should fear the rise of warlords: 

The longer that Kiev and Moscow practice what amounts to a military stalemate, the more opportunity local armed actors have to change the actual power balance on the ground.  They can ensure that either the Russian or the Ukrainian state that eventually triumphs will have to bargain with them in the future.Once ensconced in positions of local power, warlords and their threats of violence are hard to dislodge.

Through it all, Ukrainian officials are hoping to follow through with elections, slated for the end of this month, to replace ousted Ukrainian president Viktor Yanukovych and his cabinet, permanently.