The official met with President Volodymyr Zelensky to discuss the Zaporizhzhia plant, amid worries that a Ukrainian offensive could raise the already-high risk of disaster.
Of 81 missiles fired, six were hypersonic weapons, among Russia’s newest and most advanced, which are all but impossible to shoot down. The attacks killed at least nine people.
A Ukrainian official urged civilians to leave the eastern bank of the Dnipro River, across from the city of Kherson, warning of the “possible intensification of hostilities” there.
Officials urged Ukrainians to continue conserving energy, as analysts said that deteriorating weather was one factor slowing Ukraine’s battlefield progress.
President Biden’s remarks reflect the urgent concern in Washington and among Western allies that Russia may be searching for a pretext to unleash a battlefield nuclear weapon.