As a former part of the Soviet Union, Ukraine, especially the Black Sea region, has long been the focus of the power games between the United States and Russia.

For nearly two decades, the US government has done its utmost to seek strategic dominance in Ukraine. Now the "Color Revolution" the US has tried to promote in Ukraine and its provision of large-scale aid to Ukraine's pro-West opposition have directly resulted in the current crisis in the East European nation that has ousted its nationally elected president via what Russia described as a coup.

As the US strategist and former US national security advisor Zbigniew Brzezinski points out in his book The Grand Chessboard: American Primacy and Its Geo-strategic Imperatives, Ukraine is an important part of the US' Eurasian chessboard. The US believes if Ukraine is an independent nation it will help squeeze Russia's geostrategic space and contain Russia's reemergence. Without the support of Ukraine, which boasts a population of 52 million, important resources and Black Sea ports, Russia will no longer be a Eurasian power.

Meanwhile, Russia views Ukraine and other former members of the Soviet Union as the means for it to regain its lost influence as a big power. If Moscow can retain its influence over Ukraine, it will gain capital in rebuilding itself into a power astride the Eurasian continent.

However, with Kiev indicating it is likely to forge closer links with the European Union following the ousting of President Viktor Yanokovych, this threatens both Russia's influence in Eurasia and its interests.

Moscow views its interests in the Black Sea as core national interests and thus views any encroachment on these interests as unacceptable, especially in the Crimean peninsula, which is of particular geostrategic importance to Russia as it is home to its Black Sea Fleet. Crimea was handed over to the Ukraine republic by Moscow in 1954 after being under Russian rule for about two centuries.

This is why Russian troops and military airplanes entered Crimea, and why Russian President Vladimir Putin proposed to the Russian Federal Council on March 1 the use of force in Ukraine and why the council agreed the same day that Russia can take comprehensive measures to protect the safety of Russian citizens and soldiers in its volatile neighbor.

For a long period, the differences between Ukraine's east and west in religious beliefs, languages and traditions have caused estrangement between residents in different regions.

In Ukraine's Autonomous Republic of Crimea, Russian-speaking residents comprise nearly 70 percent of the population. They want to enhance ties with Russia and even hope to become a part of Russia. MPs in Crimea have already voted in favor of becoming part of Russia, and people who live in the area will get to have their say in a referendum on March 16.