LVIV, Ukraine (AP) — Ukrainian forces claimed to have retaken a Kyiv suburb and an eastern town from the Russians in what is becoming a back-and-forth stalemate on the ground, while negotiators began assembling for another round of talks Tuesday aimed at stopping the fighting.

Ahead of the talks, to be held in Istanbul, Ukrainian President Volodymyr Zelenskyy said his country is prepared to declare its neutrality, as Moscow has demanded, and is open to compromise on the fate of the Donbas, the contested region in the country's east.

The mayor of Irpin, a northwestern Kyiv suburb that has been...