Here are five reasons the world's largest economies are watching what happens in Ukraine, according to CNNMoney.


1. Russia supplies about 25 percent of Europe's gas needs, and half of that is pumped via pipelines running through Ukraine. Moscow has cut off that flow in past disputes with Kiev, and a disruption could push up energy prices for businesses and households. The critical Crimean peninsula juts into the Black Sea, and the Russians base their Black Sea navy there.


2. Sanctions on Russia: One prospect on the table would be the unusual circumstance of one top-10 global economy placing sanctions on another. But Secretary of State John Kerry said Sunday that the U.S. is "absolutely" willing to consider sanctions against Russia, even though that is rare.


3. The impact could be felt beyond Europe if the world's supply of grain is impacted. Ukraine is one of the world's top exporters of corn and wheat, and prices could rise even on concern those exports could halt.


4. Ukraine's government is in debt and needs assistance. The country owes $13 billion in debt this year, and $16 billion comes due before the end of 2015. Without help, the country appears to be headed for default.


5. Ukraine isn't the only fragile emerging market. Ukraine's instability comes at a difficult time for emerging markets worldwide, which are seeing growth slow as the Federal Reserve eases its economic stimulus. Troubles in Ukraine will also hurt Russian banks, which have lent heavily to Ukraine.