See H.R. 4415 introduced by Rep. Adam Smith (D-WA) to make it the policy of the U.S. not to use nuclear weapons first. Congress has considerable legal standing to pass legislation that prohibits first use.
The U.S. currently retains the right to use nuclear weapons first as part of a preemptive or preventive strike, or in response to a conventional, cyber, chemical or biological attack against the U.S. or its allies. U.S. massive conventional forces, leading experts argue, are sufficient to deter these nonnuclear threats. It is therefore in U.S. interests to adopt a no-first-use policy.
Some critics in the U.S. argue that we need the credible threat of the first use of nuclear weapons to deter the nonnuclear threats noted above and that this policy gives assurance to our allies who want to ensure they are safe from an attack by Russia or China with their large conventional forces. But others argue that the U.S. has sufficient conventional forces to deter or respond to such attacks and that a first use policy creates more risks than its alleged benefits—heightening global tensions, suspicion and the danger of a devastating unintended nuclear war due to accident, miscalculation or false alarm. Imagine that, in a time of high tensions, under the stress of a major crisis, Russia falsely calculates that the U.S. is about to launch a nuclear first strike against them. They could then decide to launch their nuclear weapons first before they are hit.
China has maintained a no-first-use policy for decades as has India. A no-first-use pledge would demonstrate that the United States views its weapons as deterrents to nuclear warfare, not as tools of aggression.
The importance of acting now to adopt a no-first-use policy has been made even more imperative by the Trump administration’s recent Nuclear Posture Review, which has broadened the range of scenarios that might lead to the first use of U.S. nuclear weapons. These, it says, “include, but are not limited to, attacks on the U.S., allied, or partner civilian population or infrastructure, and attacks on U.S. or allied nuclear forces, their command and control, or warning and attack assessment capabilities.”
A no-first-use pledge, to be credible, must be accompanied by steps to reduce first strike capabilities and fears, as recommended in Step 4 by experts who have a credible, feasible plan to shift away from the current U.S. nuclear war-fighting posture to one of deterrence-only as a transition towards the ultimate goal of eliminating nuclear weapons.
“Washington and Moscow together must carefully dismount the “nuclear tiger” by reducing first-strike capabilities and fears, increasing warning and decision time for leaders and improving the survivability of their nuclear forces.”
--Former Senate Armed Services Committee Chair, Sam Nunn