Ukraine sent an armored column Tuesday to the city of Slavyansk near the Russian border, where supporters of Moscow had taken over police headquarters and set up their own checkpoints.
Acting Ukrainian President Oleksander Turchinov confirmed the first military moves by his government, announcing what he called an "anti-terrorist operation" in eastern Ukraine.
"I want to emphasize that the aim of the operation is to protect the citizens of Ukraine, to stop terror, to stop criminals and to stop attempts at tearing our country apart," Turchinov said, addressing parliament.
As tensions escalate in Ukraine, there is a brewing refugee crisis on the ground. What can be done to help? Sergey Rakhuba, with Russian Ministries, explains this and more, on CBN Newswatch, April 15.
Meanwhile, in Kiev, the Ukrainian capital, angry anti-Russian activists attacked a pro-Russian presidential candidate as he was leaving a television station, pelting him with eggs.
The escalating tension in Ukraine comes after a Russian jet buzzed a U.S. Navy ship in the Black Sea. The jet reportedly made a dozen high-speed passes over the U.S.S. Donald Cook for more than 90 minutes.
Col. Stephen Ganyard, former Deputy Assistant Secretary of State, said the incident was a warning to Washington from Russian President Vladimir Putin.
"The message is, we see you, we don't like you in our backyard, and we prefer that you would leave," Ganyard said.
The Black Sea maneuver is just one more instance of Putin thumbing his nose at President Barack Obama, who is now becoming known more internationally for his tough talk rather than forceful action.
When the president and Putin spoke for 90 minutes Monday, the White House expressed "grave concern" over Putin's support for pro-Russian militia destabilizing eastern Ukraine.
The United States fears Kiev will have no choice but to use force, and has pointed a public finger at Putin.
"We know who is behind this. Indeed, the only entity in the area capable of these coordinated professional military actions is Russia," U.S. Ambassador to the United Nations Samantha Power explained.
The administration says tough economic sanctions are beginning to take hold, and it's threatening to ratchet up sanctions even more if Russia doesn't back down.
But Putin is leveling his own sanctions against Ukraine. He has more than doubled the price of natural gas there since the pro-Russian Ukrainian President Viktor Yanukovich was ousted in February.
That makes life much tougher for people such as Yuri Kuleshov and his wife Svetlana, pensioners who live near Kiev.
"We will simply stop buying all the things we are buying now, because we have to heat the house in order not to freeze," Kuleshov said.
President Obama said he has no plans to send weapons to Ukraine, but he has received strong criticism from some Republicans, led by Arizona Sen. John McCain, who claim his actions will do little if anything to stop Putin.
McCain also criticized sanctions by the European Union. Speaking in Estonia, where residents also have concerns about a potential Russian invasion, McCain called the European Union sanctions against Russia "almost a joke."
He called for strong Western leadership headed by the United States.