Armed men who call themselves members of Ukraine's disbanded elite Berkut riot police force stand at a checkpoint on a highway that connects the Black Sea Crimea peninsula to mainland Ukraine near the city of Armyansk, on February 28, 2014 Viktor Drachev/AFP Russia's parliament authorized the use of force in Ukraine's Crimean peninsula on Saturday, spurring Ukraine to warn that military intervention would lead to all-out war.

Ukraine has been in turmoil in recent months amid a conflict between pro-Russian and pro-Western European forces in the country. The crisis came to a head last weekend with the ouster of the country's pro-Russian president Viktor Yanukovych.

After Russia approved the use of force Saturday, Ukraine asked the United States and other members of the United Nations to help keep the country safe. Crimea — the area of Ukraine that Russia is seizing control of — is a semi-autonomous region within Ukraine that is largely pro-Russia.

Rusisia began to take hold of Crimea even before President Vladimir Putin announced he was asking Parliament for permission to send troops in. Armed Russian soldiers surrounded the Crimean capital, blocked off streets, and even closed the airport when they deployed there on Friday, The New York Times reported.

Russia has said it needed to send soldiers in to Crimea to ensure the safety of Russian citizens and soldiers stationed there.

The presence of armed Russian soldiers in Crimea has aroused mixed feelings in the people there, even though Crimea's newly elected prime minister asked Putin to intervene. One 71-year-old Crimean told Reuters that the Russians were protecting the Crimeans, while others are more suspicious of the military presence.

U.S. President Barack Obama told Russia Friday there could be "costs" if it intervened in Ukraine, spurring one Russian lawmaker to say Obama was out of line, according to the AP. The upper house of Russia's parliament then recommended that the Russian ambassador in Washington be recalled.

The political climate in Ukraine grew tense this fall when Yanukovych went back on a promise to sign onto trade deals with the European Union. This upset many Ukrainians, who were eager to get closer to the EU and distance themselves from Russia, U.S. ambassador to Ukraine Steven Pifer explained in a Dec. 2 interview with PBS.:

Polls show more than 50 percent of the Ukrainian population now would like to get closer to Europe.

And it’s because of the living standards, but it’s also because of rule of law. For a country where there is corruption, where crony politics, they would like to have a more normal democratic system, and that is the attraction of Europe.