Ukraine's government in Kyiv has warned of a crackdown on pro-Russian protesters in the east. Moscow, meanwhile, has called the allegations it is amassing troops along the border with Ukraine "baseless."
Moscow steps up pressure
Ukraine's acting Interior Minister Arsen Avakov said Wednesday that an anti-terror operation against pro-Russian separatists in the country's east was underway and a crackdown from law enforcement could be imminent.
"For those ready for dialogue, there will be a political solution," Avakov told reporters in Kyiv. "And for the fringe for whom the most important thing is conflict, they will be met with force."
Hundreds of militants remain holed up in government buildings in Donetsk and Luhansk. They have vowed not to give up and on Wednesday said they'd fight off any attempts by the government to dislodge them. Access to the buildings is blocked by barricades of tires and razor wire.
Ukraine and the US accuse Russia of stoking anti-Western sentiment and helping to fuel the protests in an attempt to instigate another military intervention similar to the one in Crimea. Moscow on Wednesday rejected the allegations and said the claims it was amassing troops along the border with Ukraine were "baseless."
"The US and Ukraine have no reason for concern," the Foreign Ministry said in a statement.
The Russian Defense Ministry, meanwhile, warned NATO against moving troops near the Russian border.
"Russia has taken note of certain alliance countries' plans to station large contingents close to our borders," Deputy Defense Minister Anatoly Antonov said during a press conference, according to the Interfax news agency.
Shortly thereafter, NATO Deputy Secretary-General Alexandre Vershbow "totally" dismissed Russia's claims the alliance was planning to deploy troops near the border.
"NATO's core task is collective defense," he wrote on Twitter. "We're taking legitimate steps to deal with instability created by Russia's illegal actions."
Russia not easing tension
German Chancellor Angela Merkel said Russia had failed to take steps to ease tension in Ukraine, which she had expected following her phone call with President Vladimir Putin last week.
She added that Germany remained committed to dialogue with Russia.
"But on the other hand we will say loudly and clearly: Ukraine has in our view a right to choose its own path and we will insist on it," Merkel said. "Ukraine must decide on its own fate and we want to help it."
Potential four-way talks
In the first of two phone calls with his US counterpart John Kerry on Wednesday, Russian Foreign Minister Sergei Lavrov said that four-way talks with representatives from the US, Russia, Ukraine and the European Union must focus on fostering dialogue among Ukrainians.
Both Lavrov and Kerry urged all sides to avoid violence, according to the Foreign Ministry. The EU said top diplomats from the EU, Russia and Ukraine would meet next week to discuss the crisis, but Moscow said it wanted to know more about the agenda for those talks.
"Lavrov noted that this format could be useful if it is aimed not at discussing various aspects of one bilateral relationship or another, but on helping to arrange a broad and equal international Ukrainian dialogue with the aim of agreeing on mutually acceptable constitutional reform," the ministry said.