In 1997, President Bill Clinton issued Presidential decision directive (PDD) 60. This directive radically changed US stratigic nuclear policy from "launch on warning" to "retaliate after absorbing a first strike". President Clinton's justification for this change was based on the false premise that in the so-called "Post-Cold War Era", Russia and China are no longer nuclear threats.
Robert Bell, senior director for defense policy and arms control at the National Security Council, verified information about PDD 60 in an interview on December 23, 1997. Bell pointed out that while the United States has always had the "technical capability" to implement a policy of launch on warning, it has chosen not to do so. "Our policy is to confirm that we are under nuclear attack with actual detonations before retaliating".
Hello? Are you serious? The whole strategy that makes nuclear weapons a deterrent is that under a "launch on warning" policy, whichever nation launches first looses and whichever nation launches second wins. If you take US nuclear missiles off "launch on warning" and switch to a policy of "retaliation after absorbing a nuclear first-strike", there won't be anything left over to retaliate with. You loose. Especially since 1. most all US nukes are sitting in vulnerable fixed silos, and 2. the US has been unilaterally downsizing our nuclear arsenal.
"Launch on Warning" means the US would launch its nuclear missiles after it has been varified that a country like Russia and China have premptively launched on the US but before enemy warheads have arrived. Under "Launch on Warning" the US would retaliate while the enemy ICBMs are still in the air, and before they have detonated in the US.
The reason "Launch on Warning" assures that whomever launches first looses and whomever launches second wins is that a country would likely only launch 50% of its nukes during a first-strike. Most of the incoming nukes will be targeting our nukes here in the US to prevent a retaliatory counter-attack. However, how "Launch on Warning" works is the launch-second country can simply track the incoming ICBMs and predict which silos are being targeted. The US would then launch the nukes only in those targeted silos. The "launch on warning" ICBMs would then target the remaining unlaunched ICBMs back in the attacking nation. When Russia's ICBMs arrive, those nukes strike empty silos. When the US nukes arrive on the other end, they target and destroy remaining ICBMs in Russia.
If the US only uses 50% of its nukes to target the remaining Russian nukes, then the US is left with 50% remaining ICBMs and Russia is left with 0% ICBMs. This is how the "Launch on Warning" strategy assures that whomever initiates a nuclear firstrike looses and why the "Launch on Warning" policy is the only real and effective nuclear deterrence policy.
The new and current nuclear policy to "Retaliate after Absorbing a First-strike" is an unwinnable policy that does more to invite attack than deter it.
Unfortunately the only thing the public thinks it knows about nuclear stragedy is from the movie "War Games" which equates Global Thermonuclear War with a game of tick-tack-toe.