US President Barack Obama says he is revamping his country's nuclear strategy to substantially limit the conditions under which it would use nuclear weapons.

The president made his remarks in an interview with the New York Times, ahead of a formal announcement on Tuesday. The new US nuclear strategy explicitly states that, in compliance with the Nuclear Non-proliferation Treaty, nuclear weapons will not be used against non-nuclear states, even if they attack the US with biological or chemical weapons or launch a cyber attack.

Mr Obama argued that those threats could be deterred with a combination of old and new conventional weapons. He also said the US renounces the development of any new nuclear weapons. The president described his policy as part of a broader effort to make nuclear weapons obsolete and to create incentives for countries to give up their nuclear ambitions.