The main foreign policy threat to Ukraine is Russia. Ukrainian commentators have expressed the fear that if the Crimea or pro-Russian regions in Ukraine demand unification with Russia, this could spark a civil war in Ukraine with the risk of Russian intervention. Alternatively, should extremist Russian nationalists, such as Vladimir Zhirinovsky, come to power in Moscow, it is possible they would try to incorporate Ukraine into Russia.
Ukraine's internal instability and the increasingly aggressive stance of Russia toward it has been a source of concern to the US government. The Clinton administration has demonstrated a growing willingness to support the state both politically and economically. Germany and other European states also support Ukraine as a buffer to Russia. However, it is unlikely that this support will extend to accepting Ukrainian EU membership.
