Update 12:00 p.m. Turchynov's 'anti-terrorist' military operation finally appeared Tuesday, in the form of road blocks outside of Slovyansk and a short offensive to reclaim an airport in Kramatorsk

Ukraine's military set up road blocks outside of Slovyansk Tuesday morning, blocking all access to the city, which was taken control by pro-Moscow militants on Saturday. "Witnesses said a dozen armored personnel carriers parked on the highway flew Ukrainian flags about 40 kilometers, or 25 miles, north of the town," according to The New York Times.

In Kramatorsk, Bloomberg reports Ukrainian troops advanced on an airport controlled by Russian-backed militants, killing four and wounding two others after exchanges of heavy fire. Ukraine troops regained control of the airport, Turchynov announced. Stay tuned for more updates as they become available.

Original: The acting president of Ukraine said on Tuesday morning that an 'anti-terrorist' military operation has begun against pro-Russian forces within their country, but observers on the ground have yet to see any developments. Oleksandr Turchynov had previously given protesters a Monday morning deadline to put down their weapons and abandon government building that had been seized in several eastern cities, but so far there are no reports of actual fighting involving the military.

The increasingly bold actions of ethnic Russian and anti-Kiev groups in the eastern part of Ukraine has created an unusually tense situation over the last week, as legitimate fears have been raised of a further Russian incursion, beyond Crimea. Satellite images appeared to be showing a massive buildup of Russian troops along the Ukrainian border, and with no NATO or other European forces in position to meet them, it is believed the Russian army could overwhelm most of Ukraine's forces with little effort. All Moscow would need is an excuse to move in.

While the city of Donetsk appears to be the focal point of the unrest at the moment, observers are still waiting on Tuesday to see if any actual operations will take place against the protesters. President Obama and Vladimir Putin spoke on the phone on Monday night, but there appears to be no progress on attempt to find a peaceful de-escalation.