South Korea's defence minister says there's no reason to doubt the sincerity of North Korean leader Kim Jong Un ahead of a summit with President Donald Trump.

Song Young-moo says, "Just because we have been tricked by North Korea in the past doesn't guarantee that we will be tricked in the future. If we believe that, we will never be able to negotiate with them and make peace with them."

He was speaking at an international security conference in Singapore, which is hosting the June 12 summit.

Song says if the talks on North Korea's nuclear weapons are successful, they can be compared to the 1989 Malta Summit between former President George H.W. Bush and Soviet leader Mikhail Gorbachev, less than a month after the fall of the Berlin Wall.

Song says: "A dramatic change has come for the security environment of the Korean Peninsula and Northeast Asia."

The Malta summit took place on 2-3 December 1989 a few weeks after the collapse of the Berlin Wall. Bush and Gorbachev had declared the end of the Cold War, and the summit was referred to be the most important meeting since 1945, when British Prime Minister Winston Churchill, Soviet Premier Joseph Stalin and US President Franklin D. Roosevelt agreed on a post-war plan for Europe at Yalta.