(CNN) -- The upheaval in Ukraine has spiraled into an increasingly tense dispute between Russia and the West. The United States and many European countries are demanding that Moscow scale back its deployment of troops in Ukraine's southern region of Crimea. But Russian President Vladimir Putin so far appears unfazed by the pressure. By Russia's account, its soldiers are protecting the human rights of worried, vulnerable Russian speakers. But in the U.S. view, Russia is violating international law. Caught in the middle is Ukraine's shaky new government. With armed men are locked in an uneasy standoff in Crimea, the consequences could be deadly. And their effects may ripple out far beyond Ukraine's corner of Eastern Europe.
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The presence of Russian troops in Ukraine's Crimea has ratcheted up tensions
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U.S. President Barack Obama appears to have limited options to pressure Russia
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A military response isn't considered to be a realistic possibility
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The crisis is roiling global markets, pushing up the price of oil and hurting the ruble
"There are no grounds for the use of force against civilians and @placeholder, and for the entry of the Russian military contingent,"