Are we on the cusp of a new era of expanding nuclear arsenals?

For many years, it has been believed that the nuclear problem was a relic of the Cold War. To the contrary, the world is moving closer to a new era that could be defined even more sharply by nuclear weapons, as Vladimir Putin’s threats against Ukraine demonstrate, writes Richard Haass

Russian president Vladimir Putin has  threatened to use nuclear weapons in or near Ukraine in an effort to intimidate Ukrainians and force European governments and the US to rethink their support for the country. Picture: Konstantin Zavrazhin, Sputnik, Kremlin Pool Photo via AP

Nuclear weapons have been a feature of international relations since August 1945, when the US dropped two of them on Japan to hasten the end of the Second World War. 

None has been used since then, and they arguably helped keep the Cold War cold by forcing a degree of caution on both sides of the confrontation between the US and the Soviet Union.