N Korea yet to take concrete steps to dismantle nukes: Pence

US awaits concrete steps by North Korea to dismantle its nuclear weapons that threaten America and other countries in the region, Vice President Mike Pence has said.

Pence's statement comes during his address to the global chief of mission conference on Wednesday and gains significance as the White House is preparing another summit between President Donald Trump and the North Korean leader Kim Jong-un.

The two leaders have recently exchanged letters.

Kim and Trump held a historic meeting in Singapore on June 12 last year where they issued a vague goal for the "complete denuclearisation" of the Korean Peninsula without describing when and how it would occur.

Pence said that the US awaits North Korea to dismantle its nuclear weapons.

"While the president has started a promising dialogue with Chairman Kim, we still await concrete steps by North Korea to dismantle the nuclear weapons that threaten our people and our allies in the region," Pence said.

In his address, Pence also said that Russia seeks to overturn the international order that the US has upheld for more than half a century.

"Unlike the Soviet Union and its many client states, no shared ideology or objective unites our competitors and adversaries except this one. They seek to overturn the international order that the US has upheld for more than half a century," he said.

"Truthfully, it is a pact surrounding what they perceive to be a common enemy, but the truth is the US will rise to that challenge, we will stand with our allies and we will advance our values and our principles in the world," Pence added.

Targeting Iran, Pence said that President Trump is standing up to the Iranian regime which is making the west Asian nation change its ways.

"And as we stand today, Iran is now under unprecedented pressure to change its ways," he said.

"The message that the disastrous nuclear deal benefited the very mullahs who oppressed their people. And even as we've striven mightily to protect our most important interests, we've also fought hard. We've also fought hard not only to stand up to those who would challenge us but to advance American values on the world stage," Pence said.