"Ukraine stands with the U.S. The U.S. stands with Ukraine. Always and forever."
"Facing missile attacks daily, Ukraine knows well what terrorism is and sincerely sympathizes with the U.S. people. Terrorism is an evil that has no place in the modern world!" Zelensky said.
Zelensky called Russia a "terrorist state" in another tweet alerting that the Kharkiv and Donetsk regions of Ukraine were suffering from a "total blackout."
"Russian Federation terrorists remain terrorists and attack critical infrastructure. No military facilities," Zelensky said.
"The goal is to deprive people of light and heat."He added that partial blackouts were experience in the Zaporizhzhia, Dnipropetrovsk and Sumy regions of Ukraine on Sunday.
His comments came Ukrainian troops recaptured Chkalovske, a town between the cities of Kharkiv and Izium, from Russian forces as they continued their rally for territorial gains, having reclaimed about half a million acres of land.
"Another freed settlement!" Zelensky said on Telegram with a video of a soldier raising the country's banner above the village.
"The Ukrainian flag returned to Chkalovske, Kharkiv region. And it will be like that everywhere. We will expel the occupiers from every Ukrainian city and village. Thanks to all our heroes!"
Ukraine in recent days has swiftly moved to reclaim occupied territory in the northeastern part of the country, forcing Russian troops to retreat.