US President Barack Obama says America can further reduce its nuclear weapons stockpile while maintaining its strategic deterrent.
In a major foreign policy speech ahead of a nuclear security summit in South Korea, Mr Obama says Washington will work with Russia and China.
Mr Obama says he is pushing for "a world without nuclear weapons", making direct appeals to North Korea and Iran, the BBC reports.
He emphasised the US's unique position to seek change but said "serious sustained global effort" was needed.
The meeting in Seoul is being attended by representatives from some 50 countries, including New Zealand Prime Minister John Key.
Speaking to students at Hankuk University, Mr Obama reiterated the commitment of the US as ''the only nation to have ever used nuclear weapons'' to reducing its nuclear arms stockpile, reports the BBC.
He also spoke, he said, as a father who did not want to see his daughters growing up in a world with nuclear threats, a comment which drew applause from his student audience.