The U.S. attitude should also depend on the degree to which the Eurasian Union’s growth occurs on a purely voluntary basis. Moscow’s (so far unsuccessful) attempts to play hardball with Ukraine do not set a good precedent—nor do its calls for CSTO members to unanimously approve any foreign military deployment in member states, effectively giving Russia a veto over the presence of foreign forces on neighbors’ soil.

Even if Moscow is not trying to recreate the Soviet Union, schemes like the Eurasian Union are undermined by a post-imperial mindset that makes it difficult for Russia to contemplate anything like truly voluntary, mutually beneficial integration—or allowing its neighbors to prioritize relations with the U.S., EU or China. Moscow promotes regional integration to keep its neighbors within Russia’s orbit, strengthening Russian influence over their politics and constraining their ability to develop relations with outside powers.

Eurasian integration can promote stability and prosperity in much of the region—but only if it is voluntary, nonexclusive and designed for the benefit of all member states. It remains unclear whether Putin’s proposed Eurasian Union meets any of these criteria. For now, the West should be cautious, while making clear that it takes seriously the right of Russia’s neighbors to choose their own international engagements.

Jeffrey Mankoff is an adjunct fellow with the CSIS Russia and Eurasia Program.

Image: www.kremlin.ru