Russia and Ukraine are former members of the Soviet Union. In 1991, when the USSR collapsed, Ukraine became independent but remained within the Commonwealth of the Independent States, an organization dominated by Russia. However, Ukraine has always been very close to Western Europe, especially Germany, and has never accepted Moscow's domination of its affairs.

This difference of opinion led to tensions between the two countries. In particular, Ukraine refused to join the Customs Union, a trade bloc formed by Russia, Belarus, Kazakhstan, and Kyrgyzstan. Instead, it signed an Association Agreement with the European Union, which allowed it to move closer towards integration into the EU.

This difference of opinion led to tensions between the two countries. In particular, Ukraine refused to join the Customs Union, a trade bloc formed by Russia, Belarus, Kazakhstan, and Kyrgyzstan. Instead, it signed an Association Agreement with the European Union, which allowed it to move closer towards integration into the EU.

This angered the Russians, who saw Ukraine as a strategic buffer state between themselves and the West. They feared that NATO would expand eastwards towards their borders if Ukraine joined the EU.