Ukrainian President Volodymyr Zelenskyy said in an interview broadcast on Sunday that Ukraine had received "sophisticated" air defense systems from the United States.

It was the first acknowledgment that Ukraine had received the National Advanced Surface-to-Air Missile System (NASAMS), long sought by Kyiv and whose shipment was approved by Washington late last month.

Zelenskyy also thanked the United States for HIMARS and other multiple rocket-launching systems enabling Ukraine to advance against Russian forces.

Heavy fighting is taking place with Russian forces in many places along the frontline, some with "positive results" for Kyiv, Zelenskyy said in his nightly video address on Sunday.