The mission verified at least 274 civilian deaths and 1,763 injuries during the month, the highest monthly casualty toll recorded in the past four years.

Russian forces launched 118 long-range attack drones, including Shahed-type drones, against Ukraine overnight, the Air Force reported.

Freuding's comments are the latest in a series of increasingly warnings from Western leaders and defense officials about the threat emanating from Russia and Europe's current lack of preparedness.

Russian forces launched two Iskander ballistic missiles and 221 drones, 195 of which were intercepted, overnight on June 11, according to the Air Force.

Russian forces launched two Kh-59/69 cruise missiles and 168 drones, 146 of which were intercepted, overnight on June 9, according to Ukraine's Air Force.

"As of now, 11 drone strikes on (Kharkiv) have been confirmed, with two drones crashing without detonating," Kharkiv Mayor Ihor Terekhov said.

The United Nations Security Council convened on June 8 to discuss Russia's recent large-scale attacks on Ukraine, as U.N. officials warned that civilian casualties and destruction have reached some of the highest levels seen in the war in recent months.

Key developments on June 8:

• Russia rejects Ukrainian, European peace initiatives, says battlefield will decide war
• NATO jets shoot down drone over Latvia in 1st such interception, military says
• Ukraine strikes Russian oil depot, radar station, other military targets, General Staff confirms
• Ukraine foils Russian plot to assassinate senior military