A Russian military foothold in the southeast would make any scenario to end this war costlier in lives and resources. Ukraine has sustained billions of dollars in damages from the ongoing invasion, and Russia’s control of Ukraine’s southeast would mean Ukraine’s loss of access to the Sea of Azov and, and largely, to the Black Sea. Russia’s invasion is already blocking millions of tons of grain in Ukrainian ports, threatening global food security. Ukraine’s southeast also has many industrial assets. Some companies, such as Ingas in Mariupol, which produced neon for semiconductor lasers, have halted their operations. The town of Severodonetsk and its surrounding area—one of the primary targets of Russia’s ongoing offensive—hosts major chemical enterprises. The southeast holds important logistical routes, such as Tokmak, a key road junction east of Zaporizhzhia. Preserving the southeast is critical for Ukraine’s long-term economic viability.

Russia may set conditions for a future offensive on Odesa, a city that Russia requires to establish a land bridge to Transnistria. The Kremlin has recently put Russian forces in Transnistria on alert and has likely conducted false-flag attacks there—presumably to pressure Ukraine and possibly to set conditions to destabilize Moldova.

A Russian foothold would also threaten other countries, including those in NATO. The Kremlin will likely try to link its territorial gains across Ukraine and potentially beyond by annexing or otherwise integrating other territories that Russia illegally occupies. Russia has repeatedly demonstrated its willingness to limit the freedom of navigation of other countries in the Black Sea. Ukraine is not the only country Putin has been trying to control; Moldova has been high on the list for years.