Ukraine could be about to carry out a "large-scale anti-terrorist operation" on pro-Russian separatists in several cities in eastern Ukraine after the rebels ignored a deadline to stand down.
Militias have taken control of the city of Slaviansk by seizing government buildings and setting up barricades on the outskirts of town. There have already been casualties after the government launched an operation yesterday.
Gunmen have also taken over administrative buildings in Donetsk, which has become one of the centers of pro-Russian protests. The governor of the Donetsk region has said that a government operation has started, although journalists on the ground hadn't seen any sign of it.
Russia has warned Ukraine not to use force against the militias, but Ukraine and the U.S. blame Russia for the escalation.
The increasing tension has hit Russian markets, with the Micex -1.65% and USD-RUB +0.9% at 35.963 rubles.