KYIV, Ukraine—Ukraine’s foreign minister called on the country’s allies not to fear a possible breakup of the Russian state as a consequence of the war, while defending Kyiv’s right to strike targets on Russian soil and vowing that Ukraine would never accept a peace settlement that leaves occupied lands, including Crimea, under Moscow’s control.

Though Ukraine’s Western allies are united over the goal of preventing a Ukrainian defeat, not all embrace the objective of a full-blown Ukrainian military victory, with Kyiv regaining not just the lands it lost since the February invasion but also the Crimean Peninsula and the parts of the eastern Donetsk and Luhansk regions that fell under Russian rule in 2014.