We expanded the circumstances under which the United States would consider nuclear first use.

In other words, we expanded the circumstances under which the United States would consider nuclear first use. pic.twitter.com/ObT34ksqAv

— Kingston Reif (@KingstonAReif) April 26, 2020

An attack on our civilian population of any sort could be viewed as a threat which could be met with the first use of nuclear forces according to that document.

h/t Builder