We begin with a fast and unpredictable developments in the showdown with Russia. Today, president Obama's challenge to Russia's invasion of Ukraine, and deploying fighter jets to the region. Russian... See More
We begin with a fast and unpredictable developments in the showdown with Russia. Today, president Obama's challenge to Russia's invasion of Ukraine, and deploying fighter jets to the region. Russian president Vladimir Putin, digging in. And there is word, tonight, that the two of them have spoken. But all of this is creating new concern that the world's superpowers are being pushed into a dangerous corner. And ABC's chief global affairs correspondent, Martha Raddatz, on the crisis and what is happening right now. Reporter: The crisis escalating with dizzying speed. Tonight, pro-russian protesters in eastern Ukraine tried to knock over a bus. As the Russians tighten their grip around the crimean peninsula. In just the past 24 hours, a high-stakes game of chess. Pro-russian authorities push crimea's parliament to call for a vote to officially become part of Russia. The U.S. Calls that illegal and moves forward with sanctions. The Russians tighten their grip on crimea, sealing the borders and using a sunken ship to block a port. The U.S. Sends fighter jets to the region to help nato monitor the skies. Events all so alarming, president Obama gave a hastily-prepared warning to the Russians, to send their troops back to barracks. In 2014, we are well beyond the days when borders can be redrawn over the heads of democratic leaders. Reporter: But whatever warnings the president gave today, vladmir Putin has heard them before and keeps playing this dangerous game without fear, no matter what the U.S. Or the world does. The U.S. Is left to react to Putin's moves, which are mysterious. So much so, in the past, the Pentagon has even analyzed the Russian leader's body language, trying to predict what he'll do next. All this while fresh talks here in Europe between secretary of state John Kerry and Russia's foreign minister end with zero progress and increased irritation. Having Russian boots on the ground and Russian tanks is unacceptable in the 21st century. And who knows the limits, tell me? Reporter: That is the urgent question tonight. Will the Russians stop with just crimea? Or invade further into Ukraine? Ignoring the calls for America and the world to stop.
This transcript has been automatically generated and may not be 100% accurate.