The two largest nuclear powers on the planet, the United States and Russia have enough nuclear weapons to effectively end human civilization. Russian President Vladimir Putin and US President-elect Donald Trump both agree that’s not nearly enough.
Putin presented the effort as a need to adapt to changes in the world, and to ensure that Russia retains the ability to “neutralize threats” and can reliably penetrate future missile defense systems with their massive nuclear arsenal.
Trump’s comments were a lot less specific, saying that the US needs to “greatly strengthen and expand” their nuclear weapons capability, adding that he’d just keep expanding the American arsenal “until the world comes to its senses regarding nukes.”
The New START Treaty intends to limit the number of nuclear weapons both the US and Russia are deploying at any given time, and with both Russia and the US are currently on track to meet the goals of that treaty, it doesn’t seem to be the general trend in the future.
Estimates on the cost of the US “modernization” scheme for its nuclear arsenal are that it will be in excess of $1 trillion. These figures have steadily risen in recent years, and doesn’t factor in the “expansion” of arsenal Trump is talking about on top of the modernization.
US hawks have argued that the massive arsenal they already have been sitting on for decades is old and therefore some of the bombs might not work, though given the nature of a full-scale nuclear war and arsenals capable of wiping out the species several times over, being down to 80% or 90% of the warheads detonating doesn’t realistically change the result.
Still, both nations virtually bankrupted themselves during the Cold War building these huge caches of weapons, and the massive amount of money being thrown around on such projects is the sort of thing officials salivate about, meaning practical needs ends up beside the point.