KOSTYANTYNIVKA, Ukraine (AP) -- Masked and armed militants on Monday seized a council building in yet another city in eastern Ukraine, expanding their onslaught in the region, while Barack Obama said the U.S. would levy new sanctions on Russians for Moscow's alleged involvement in the unrest.
The building housing the city hall and the city council in Kostyantynivka, just 160 kilometers (100 miles) from the Russian border, was seized by masked men who carried automatic weapons. About 15 armed men, some wearing a symbol of the pro-Russian movement, guarded the building.
Kostyantynivka is just 35 kilometers south of Slovyansk which has been in insurgents' hands for more than three weeks now.
Since November, Ukraine has been engulfed in its worst political crisis since the 1991 fall of the Soviet Union. Months of anti-government protests in the capital Kiev culminated in President Viktor Yanukovych fleeing to Russia in late February.
Ukraine's acting government and the West have accused Russia of orchestrating the unrest, which they fear Moscow could use as a pretext for an invasion. Last month, Russia annexed Crimea weeks after seizing control of the Black Sea peninsula.
Seeking to ratchet up pressure on Russian President Vladimir Putin, President Barack Obama on Monday said the United States will levy new sanctions on Russian individuals and companies in retaliation for Moscow's alleged provocations.
Obama said the targets of the sanctions would include high-technology exports to Russia's defense industry. The full list of targets will be announced by officials in Washington later Monday and are also expected to include wealthy individuals close to Putin.
The European Union is also planning more sanctions, with ambassadors from the bloc's 28 members to meet Monday in Brussels to add to the list of Russian officials who have been hit by asset freezes and travel bans.
On Sunday, Pro-Russian militants in camouflage fatigues and black balaclavas paraded captive European military observers before the media and showed three captured Ukrainian security guards bloodied, blindfolded and stripped of their trousers and shoes, their arms bound with packing tape.
The provocative displays came as the increasingly ruthless pro-Russian insurgency turns to kidnapping as an ominous new tactic.
Dozens of people are being held hostage, including the seven observers from the Organization of Security and Cooperation in Europe, journalists and pro-Ukraine activists, in makeshift jails in Slovyansk, the heart of the separatists' territory.
Nataliya Vasilyeva in Moscow and Julie Pace in Manila, Philippines, contributed to this report.