Russian President Vladimir Putin has threatened to strike Ukraine again with a new nuclear-capable ballistic missile following Moscow’s latest widespread attack on critical energy infrastructure.

Vladimir Putin has approved an updated nuclear doctrine, saying that Russia could consider using nuclear weapons if it is subject to a conventional missile assault on it supported by a nuclear power.

Russian President Vladimir Putin praised President-elect Trump as an “intelligent” and “experienced” leader Thursday, while noting he does not believe the president-elect is “safe” following the two attempts on his life earlier this year.