Damaged car with a letter 'Z' in seen in the recently liberated town of Kupiansk

A damaged car with a letter ‘Z’ in seen in the town of Kupiansk, recently liberated by the Ukrainian Armed Forces.

IZIUM, Ukraine — Ukraine said its troops have marched farther east into territory recently abandoned by Russia, paving the way for a potential assault on Moscow’s occupation forces in the Donbas region as Kyiv seeks more Western arms.

In a sign of nervousness from a Moscow-backed administration in Donbas about the success of Ukraine’s recent offensive, its leader called for urgent referendums on the region becoming part of Russia.