Russian President Vladimir Putin has sought to cast a nuclear shadow over Russia’s full-scale invasion from the beginning. Three days after Russian troops crossed Ukraine’s borders in the north, east, and south, Putin said he had put Russian nuclear forces on “special combat readiness.” The U.S. Defense Department later observed that it had seen no change in the status of Russian nuclear forces.The Kremlin’s most recent attempt to play the nuclear card came on May 6. The Russian Defense Ministry announced it would hold an exercise involving non-strategic (tactical) nuclear weapons in Russia’s Southern Military District near the Ukrainian border. The Russian military has routinely conducted such nuclear exercises; the only difference was that they announced it in advance this time.Opinion: Why South Africa’s election matters for UkraineSouth Africans will flock to the polls on May 29 for the country’s most important general election since the advent of its non-racial democracy in April 1994.