SINGAPORE : North Korea will not get any sanctions relief until it has demonstrated "irreversible" steps to denuclearisation, US Defense Secretary Jim Mattis said Sunday. Speaking at a security conference in Singapore ahead of a planned summit between President Donald Trump and North Korean leader Kim Jong Un, Mattis said it is vital that the international community keeps UN Security Council sanctions in place for now.

"North Korea will receive relief only when it demonstrates verifiable and irreversible steps to denuclearisation," Mattis said during public remarks at a meeting with the South Korean and Japanese defence ministers. "In this moment we are steadfastly committed to strengthening even further our defence cooperation as the best means to preserving the peace."

South Korean Defence Minister Song Young-moo said that given recent developments in North Korea, "one can be cautiously optimistic as we go forward". Mattis has tended to stay away from commenting publicly on the upcoming summit, which Trump has confirmed will take place in Singapore on June 12, and instead deferred to the State Department.