Red line.

Putin is once again attempting to sway Western politicians by drawing another so-called "red line," suggesting that crossing it could trigger war with NATO.

However, this is unlikely for several reasons:

1. Russia Cannot Win a Conventional War Against Europe: In a conventional conflict, Russia would struggle even against Europe alone, and a nuclear war would be tantamount to suicide. Putin is not willing to commit national suicide over Ukraine. Even if he were irrational enough to consider it, his generals and most oligarchs are not. They are unlikely to sacrifice their own lives and those of their families for a war that Putin initiated and could end at any time.

2. History Shows Nuclear Powers Avoid Using Nukes, Even When Losing Wars: There are multiple precedents where nuclear-armed nations have lost or nearly lost wars without resorting to nuclear weapons. The Soviet Union didn’t use them when it withdrew from Afghanistan, the U.S. didn’t resort to them in Vietnam, and Israel refrained from using them despite facing a multi-front attack from Arab states. In the case of Russia, there is no existential threat justifying the catastrophic diplomatic, economic, and military consequences of using nuclear weapons simply because its military campaign in Ukraine is being resisted.

More importantly: Succumbing to Nuclear Blackmail Increases the Risk of Nuclear Conflict

Caving to nuclear threats only emboldens further aggression. If the use of nuclear threats achieves foreign policy goals, more threats will follow, increasing the chances of miscalculation and escalation. Worse, other countries may conclude that they, too, must acquire nuclear weapons—either to assert their foreign policy aims or to defend themselves—further heightening the risk of nuclear conflict.