Ten days ago, President Vladimir Putin announced that "any means necessary" will be used to defend the Ukrainian Donbas regions that Russia recently annexed. He was clearly referring to nuclear weapons. Given Putin's aggressive moves in Crimea and Ukraine, it's likely that he will follow through on this threat if Ukraine's recent counteroffensive continues to succeed.
Since well before their foolish invasion, the Russian leadership's primary demand has been that Ukraine reject any possibility of NATO membership. Ukraine vigorously seeks NATO membership and European Union membership. Russia does not object to Ukraine joining the EU, but it invaded Ukraine precisely in order to force Ukraine to remain outside of NATO. A simple Ukrainian pledge to remain neutral would probably have prevented the entire war, but at this point Russia will also want at least a portion of the Donbas region and is willing to use nuclear weapons to force Ukraine into such an agreement.
Nuclear weapons use might begin with a Russian hydrogen bomb demonstration, perhaps in the Black Sea near Odessa. A similar demonstration was recommended by U.S. nuclear weapons scientists toward the end of World War II, but our government rejected this advice and instead dropped the world's first nuclear bomb on Hiroshima. Russia would probably demonstrate one of their many 800-kiloton bombs. For comparison, the "Little Boy" bomb that destroyed Hiroshima had a yield of 15 kilotons. That is, the explosion released the amount of destructive energy that would be released by 15,000 tons of TNT.
Once the first weapon is exploded, one can only speculate on what happens next. I am not privy to Russian "tactical" (small) nuclear weapons, but they probably have something similar to the U.S. B61 nuclear fusion bomb. This is delivered by airplane and has a variable yield that can be set as low as 0.3 kilotons or as high as high as 340 kilotons. The lowest setting is equivalent to 300 tons of TNT. For comparison, the largest conventional bomb in the U.S. arsenal is the Massive Ordnance Air Blast (MOAB), aka the "Mother of All Bombs." It packs nine tons of TNT. For another comparison, each rocket fired by the U.S. Multiple-Launch Rocket System carries 200 pounds (0.1 tons) of high explosive. The lowest setting on the U.S. B61 bomb is 3,000 times larger than this.
I conclude that the smallest tactical nuclear weapons are thousands of time larger than the weapons currently employed in Ukraine. Once weapons of this magnitude are employed on a battlefield, all bets are off.
NATO has 4,200 nuclear weapons stored in France, Britain, Belgium, Germany, Italy, Netherlands and Turkey. Escalation could quickly go global. As nuclear war intensifies in Europe, Russia and America will be gripped by fear of the other side launching a massive first strike in an effort to reduce damage to itself. Fortunately, both sides have significant submarine-based nuclear forces that are invulnerable to such a first strike. The U.S. has several such submarines in the oceans at secret locations at all times. Both sides also have intercontinental bomber forces that could become airborne as soon as missiles from the other side are launched.
Unfortunately, both sides have massive land-based Inter-Continental Ballistic Missile forces that are sitting ducks for the other side's missiles. Both sides know precisely where the other side's ICBMs are located. Our ICBM force can deliver 800 bombs, each with a 300-kiloton yield. Russia could significantly reduce damage to itself by striking these missiles first. The U.S. and Russia have made big mistakes by not dismantling this leg of their "strategic triads."
As a measure of global overkill, consider the U.S. nuclear submarines. We have 18 of these, with four deployed underwater at all times and more deployed at times of tension such as today. Each boat packs 24 ICBMs, each ICBM carries eight hydrogen bombs that can be directed to diverse targets, and each bomb carries 120 kilotons of explosive power -- the equivalent of eight Hiroshima bombs. The 192 bombs from just one boat are sufficient to devastate Russia and, in fact, the planet.
Russia and America each have about 6,000 strategic nuclear weapons. The authoritative book "The Button," co-authored by former U.S. Secretary of Defense William Perry, states that U.S. nuclear weapons can be launched at the order of a single person, the president. President Putin has similar power.
The world has reached a shamefully dangerous point. My hope is that sensible people all over the world will join together to stop the madness.