Russia needs Ukraine if it is to build the so-called Eurasian Union, the economic bloc that Putin is seeking with Kazakhstan and Belarus. Unlike the parties to a free-trade agreement, the members of a customs union like the one Putin envisages set trade policy with respect to third states through the establishment of common foreign tariffs.
欧亚联盟是普京着力和哈萨克斯坦及白俄罗斯打造的经济集团，而乌克兰的参与是所谓欧亚联盟所不可或缺的。与自由贸易协定缔约国不同，普京想象中的关税同盟成员通过征收共同对外关税来制定与第三国的经济政策。因此，乌克兰的加入与欧盟联合协议是相违背的。