American Ambassador to Ukraine in an interview on September 19, 2022, recalled that US President Biden warned Putin about the consequences in case of using nuclear weapons.
Source: US Ambassador to Ukraine Bridget Brink
The administration of the US president and in dialogue with partners is discussing a response plan to the radical actions by the Russian Federation, such as the use of nuclear weapons in Ukraine.
When asked if the US would allow a scenario where Russia would launch a nuclear strike with tactical warheads or use the occupied Zaporizhzhia nuclear power plant as a weapon, the Ambassador noted that US President Joe Biden clearly emphasized that talks about the use of nuclear weapons are absolutely irresponsible.
“President Biden clearly said that any use of nuclear weapons will be unacceptable and will cause severe consequences. We are working together on this in the USA and discussing with our partners how we could act in response to these actions that would be absolutely unacceptable and the President has very clearly informed Ukraine about that.”
See also: Ukraine received high-precision Excalibur munitions from the USA