According to UCUSA:
China has had an unconditional no-first-use(NFU) policy since it first developed nuclear weapons in 1964
Russia had a No-First-Use policy from 1982 until 1993, when it changed its policy out of fear that its weakened conventional forces could no longer deter the United States without the threat of use of nuclear weapons. In 2018 when the United States pulled out of the INF treaty, Russia redeclared a NFU policy.
The United States has never expressed a NFU policy. In the United States the threat of nuclear response underwrites it's conventional forces. As NATO faced a massive discrepancy in armor with the Soviet Union facing Europe from the 1970s through the 90's the United States made a nuclear response a deterent against Soviet Conventional Invasion of Europe. The US which doesn't maintain an individual biological weapons deterrent uses its nuclear response as a deterrent against biological weapons, as it did in Iraq. When George W. Bush was in office he created a Cyber Command, and at the time extended the nuclear deterrent to cyber attacks. The US would deter cyber attacks against its Nuclear Power infrastructure with nuclear weapons.
The United States position on NFU was last reviewed by President Obama who entered into treaties to reduce the number of nuclear weapons in the world and was a proponent of aggressive Nuclear Arms control. President Obama declined to change the nations NFU position.
My question is whether NFU is on the table after the 2020 election in the United States; and if so, how likely is it.
Joe Biden's 2017 Speech:
Remarks by the Vice President on Nuclear Security
Wednesday, January 11, 2017
... Given our non-nuclear capabilities and the nature of today’s threats—it’s hard to envision a plausible scenario in which the first use of nuclear weapons by the United States would be necessary. Or make sense. President Obama and I are confident we can deter—and defend ourselves and our Allies against—non-nuclear threats through other means.
The next administration will put forward its own policies.
But, seven years after the Nuclear Posture Review charge—the President and I strongly believe we have made enough progress that deterring—and if necessary, retaliating against—a nuclear attack should be the sole purpose of the U.S. nuclear arsenal.