Russia can likely seize as much of Ukraine’s territory as it chooses. But plans to pacify Ukraine will require far more than the reserve forces Putin has suggested might occupy the territory as “peacekeepers” after initial combat objectives are met. Thanks to Putin’s aggression, anti-Russian fervor and homegrown nationalism have surged in Ukraine. Ukrainians have spent the last eight years planning, training, and equipping themselves for resisting a Russian occupation. Ukraine understands that no U.S. or NATO forces will come to its rescue on the battlefield. Its strategy doesn’t depend on turning back a Russian invasion, but rather in bleeding Moscow so as to make occupation untenable.

Any future insurgency will benefit from Ukraine’s geography. The country is bordered by four NATO states: Hungary, Poland, Romania, and Slovakia. Belarus, a Russian ally, is itself bordered by Poland on the west and another NATO member—Lithuania—on the north. These long borders offer the United States and NATO an enduring way to support Ukrainian resistance and a long-term insurgency and to stoke unrest in Belarus should the United States and its allies choose to covertly aid opposition to Lukashenko’s regime.

Moldova, to the southwest of Ukraine, is also an intriguing player. Although nominally neutral (neutrality is written into its constitution), Moldova has cooperated in the past with the United States and NATO; it has a somewhat frigid relationship with Moscow thanks to ongoing tensions over the breakaway republic of Transnistria, a narrow strip of land along the Moldovan-Ukrainian border. Moscow props up this separatist entity, which is garrisoned by Russian troops in the name of “peacekeeping.” Its role in Transnistria is pushing Moldova toward the West. Last November, Maia Sandu, a former Moldovan prime minister, defeated the Russia-backed incumbent president. Moldova is not likely to overtly provoke the Kremlin, but Sandu might be willing to covertly cooperate with Ukraine’s resistance.