"Just like the bombs that destroyed Hiroshima and Nagasaki, any future attack by a single tactical nuclear weapon near a densely populated area would kill tens to hundreds of thousands of noncombatants, as those did. Thus, virtually any threat of first use of a nuclear weapon is a terrorist threat. Any nation making such threats is a terrorist nation. That means the United States and all its allies, including Israel, along with Russia, Pakistan, and North Korea.” ― Anti-war activist famous for the Pentagon Papers Daniel Ellsberg (4/7/1931 - 6/16/2023), from "The Doomsday Machine: Confessions of a Nuclear War Planner" (2017).
There are two nations today that casually threaten a first nuclear strike: North Korea and Russia. North Korea is still working on its nuclear capability; Russia has long had it. Russia's terrorist dictator Vladimir Putin has dreams of recapturing the land lost when his beloved Soviet Union collapsed, with several sovereign states breaking away. One, Ukraine, has been on the receiving end of Putin's threats to use tactical nuclear weapons, a modern "fire bell in the night" to the world community.