The Kremlin's statements on the possible use of nuclear weapons are "absolutely unacceptable" and Kyiv will not give into it, Ukraine's Foreign Minister Dmytro Kuleba said early on Sunday.
Russian President Vladimir Putin and other Russian officials, including Foreign Minister Sergei Lavrov, have mentioned nuclear weapons as an option in extremis.
"Putin's and Lavrov's irresponsible statements on the possible use of nuclear weapons are absolutely unacceptable," Kuleba wrote on Twitter. "Ukraine won't give in. We call on all nuclear powers to speak out now and make it clear to Russia that such rhetorics put the world at risk and will not be tolerated."
(Reporting in Melbourne by Lidia Kelly and in Ottawa by David Ljunggren; Editing by Daniel Wallis)