Trump's nuclear review retains key Obama commitment
The Trump administration's Nuclear Posture Review retains a commitment, first made by Obama in 2010, not to "use or threaten to use nuclear weapons against non-nuclear weapons states that are party to the NPT [Non-Proliferation Treaty] and in compliance with their nuclear nonproliferation obligations." Today, all 184 non-nuclear weapons states under the treaty meet that criterion.
Trump's reaffirmation of this pledge, known as a negative security assurance, is significant. It rules out U.S. nuclear retaliation against these countries, even if they were to use chemical, biological, cyber or other weapons against the U.S. or its allies.