Russian forces attacked civilian infrastructure in Ukraine on Monday and Tuesday, killing at least 20 people. Ukrainians have been warned of a "high probability" of further missile strikes.

The attacks targeted power stations and other utilities. Russian commanders say they are retaliating for an attack on Saturday on their main supply line, a bridge that links Russia to Crimea.

Defense ministry officials say they hit all their "designated targets" and achieved their goals. However, they also struck residential buildings, a medical facility, and a playground.

The attacks drew a rebuke from NATO Secretary General Jens Stoltenberg.

He said, "Ukraine has the momentum and continues to make significant gains while Russia is increasingly resorting to horrific and indiscriminate attacks on civilians and critical infrastructure."

Stoltenberg added that Russian President Vladimir Putin started the war and must end it by withdrawing his forces.

Putin is set to meet with Turkish President Recep Tayyip Erdogan on Thursday at a regional summit in Kazakhstan. Erdogan has offered repeatedly to broker peace talks. Russian officials say they have not received any such proposal. However, they say the situation is changing "dynamically."