Russia’s invasion of Ukraine shows the limits of nuclear deterrence
Since Russia invaded Ukraine on February 24, Russian President Vladimir Putin has given orders to increase the alert level of Russia's nuclear forces and has made veiled nuclear threats.
Russia's nuclear weapons deter the West from intervening with conventional military forces to defend Ukraine.
In the current crisis, Putin clearly wants the US and NATO to know that if the West were to intervene with military force on behalf of Ukraine, he might reach for his so-called tactical nuclear weapons.
Russia also possesses some 2,000 tactical nuclear weapons kept in storage facilities throughout the country, developed to be used against troops and installations in a small area or in a limited engagement.
These are not the only tactical weapons that could be deployed; the United States has about 100 nuclear "Gravity bombs" stationed around Europe.
Tactical nuclear weapons exist because each side fears it would be deterred from using its big city-razing weapons by their very destructiveness.
No one knows if using a tactical nuclear weapon would trigger full-scale nuclear war.
In testimony before the House Armed Services Committee on February 6, 2018, then-Secretary of Defense James Mattis stated "I do not think there is any such thing as a tactical nuclear weapon. Any nuclear weapon used any time is a strategic game changer." Russian leaders have made clear that they would view any nuclear attack as the start of an all-out nuclear war.
The 77-year-old tradition of nuclear nonuse-the nuclear taboo-is the single most important accomplishment of the nuclear age.
That's why, despite the trillions of dollars spent on nuclear arsenals, no one sleeps soundly under a nuclear umbrella-especially during a crisis such as Russia's invasion of Ukraine.