Russian forces carried out massive missile strikes on cities across Ukraine for a second day on Tuesday, causing more civilian casualties.

Russia's defense ministry said its forces attacked Ukraine's command posts and energy infrastructure.

The Ukrainian State Emergency Service said it had confirmed that Russian attacks on Monday killed 20 people, including civilians, and injured 108 others.

Ukrainian President Volodymyr Zelenskyy stressed on Tuesday that his country is responding to the attacks. He said there had been 28 missiles fired by Russian forces as of Tuesday morning, and 20 of them had been shot down. He said the government is working quickly to restore infrastructure.

Zelenskyy urged the international community to step up sanctions and political pressure on Moscow. He said, "For such a new wave of terror there must be a new wave of responsibility for Russia."

NATO Secretary General Jens Stoltenberg told reporters on Tuesday, "Russia is increasingly resorting to horrific and indiscriminate attacks on civilians and critical infrastructure."

NATO says defense ministers of its member nations will hold a two-day meeting from Wednesday to discuss strengthening support for Ukraine.