Barack Obama is set to outline a new defence strategy that would limit the circumstances in which the US would use nuclear weapons.
It is expected that in future there would be no nuclear response on non-nuclear countries that comply with the Non-Proliferation treaty.
But in an interview with the New York Times, the President said that conditions would not change for countries like Iran and North Korea deemed to have violated the Treaty.
In a major speech on nuclear policy in Prague a year ago, the President said the US would take concrete steps towards a world free of nuclear arms, and urged others to do the same.
Last October, in a decision that caused widespread surprise, President Obama was awarded the Nobel Peace Prize – partly for what the Nobel committee described as his efforts to promote nuclear disarmament.
The details of the President’s new plan are to unveiled later today.
It comes ahead of a new nuclear arms reduction pact due to be signed in Prague on Thursday between Barack Obama and his Russian counterpart Dmitry Medvedev. Agreed last month, the pact commits both countries to big cuts in warheads.