Ukraine’s forces continued their rapid advance in the Kharkiv region on Sunday, exploiting an extraordinary collapse of Russian defenses and raising the question of how far they can go.

Unconfirmed reports overnight suggested Kyiv’s troops had taken Velykyi Burluk, a town about 90 kilometers east of Kharkiv and not far from the Russia-Ukraine border. The town of Chkalovske was also retaken, and all eyes are on strategically located Izyum.

"We are starting to advance not only to the south and to the east in the Kharkiv areas but also to the north. 50 kilometers is left until we reach the state border,” Ukraine’s top commander, Valery Zaluzhnyi, said in a Telegram post.