But where exactly is Ukraine in relation to Europe and Russia and how did it come to be a sovereign nation?
VIDEO: Why is Russia invading Ukraine? Countries share complex history, but Putin attack for simple reason
Why is Russia invading Ukraine? Countries share complex history
Well first, Ukraine is on the edge of eastern Europe and Russia. Its population is 43 million which is only slightly more than the state of California.
Physically, Ukraine is the size of Texas.
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Its largest city, Kyiv, is the capital and home to nearly three million people which is about the same as Chicago.
The time difference from San Francisco to Kyiv is 10 hours. So, if it's 6 p.m. on the West Coast, it's 4 a.m. tomorrow in Ukraine.
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Ukraine is Europe's poorest country and the second largest. It became independent in 1991 when the former Soviet Union dissolved.
Ukraine shares borders with Russia, Belarus, Poland, Slovakia, Hungary, Romania, and Moldova, all countries that "used to" have close ties to the former USSR.
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The southern border of Ukraine is along the Black Sea.
This was the site of the War in Donbas, led by Russian separatists which led to the annexation of Crimea by Russia in 2014.