The Kremlin spent much of the last week warning foreign diplomats and bystanders to evacuate Ukraine's capital, warning that an escalation in airstrikes is imminent, in response to Ukraine's own drone swarms sent against Moscow and other Russian sites last month - especially the Starobelsk dormitory attack.

"In response to terrorist attacks by the Kyiv regime, the Russian Armed Forces launched a large-scale strike using long-range, high-precision air, land and sea-based weapons — including hypersonic aero-ballistic missiles and attack drones," the Russian Defense Ministry (MoD) said in a statement. "The objectives of the strike were achieved. All designated targets were hit," it added.

In the wake of these devastating overnight attacks, Ukraine is reporting that at least 18 people were killed and over 100 more wounded. The hours-long assault was clearly one of the biggest and deadliest of the last year or more.

Ukraine's air force tallied that over 640 drones were sent and 73 missiles were fired on various cities, including Kyiv, and Dnipro, as well as several eastern cities, including Kharkiv and Zaporizhzhia. Ukraine claims it intercepted the majority of these, but still dozens of projectiles made it through to impact.

Kyiv Mayor Vitali Klitschko later confirmed that six people were killed in the Ukrainian capital and that at least 66 others, including two children, were wounded.

There was mayhem as people fled to shelters during the nighttime "mass enemy attack". The mayor had warned while it unfolded: "Explosions in the city. Air defense forces are working! Stay in shelters!"

Central Ukraine's Dnipropetrovsk region also saw high casualties, with at least 12 people killed and 36 others wounded. The regional governor reported that children were among the injured.

Moscow has not owned up to inflicting civilian casualties in the fresh overnight assault, but has instead framed this as part of its previewed "systematic and consistent strikes" on Ukraine's military infrastructure.

President Putin and top military brass had last month said strikes would be initiated against "decision-making centers" in response to the dorm attack in the Russia's Lugansk People's Republic on May 22, which killed 21 people - mostly teenage girls - and injured 70 others.

Kremlin officials now say that Russian forces have "a right to dismantle any infrastructure that supports terrorism."