US president Donald Trump has announced he will hold a two-day summit with North Korea leader Kim Jong Un in Vietnam later this month.
Mr Trump has said his outreach to Mr Kim and their first meeting last June in Singapore opened a path to peace. But there is not yet a concrete plan for how denuclearisation could be implemented.
"As part of a bold new diplomacy, we continue our historic push for peace on the Korean Peninsula," Mr Trump said in his State of the Union address.
Director of National Intelligence Dan Coats told Congress last week that US intelligence officials do not believe Mr Kim will eliminate his nuclear weapons or the capacity to build more because he believes they are key to the survival of the regime.
Speaking on Tuesday Mr Trump said: "If I had not been elected president of the United States, we would right now, in my opinion, be in a major war with North Korea."
"Much work remains to be done, but my relationship with Kim Jong Un is a good one."
As he faced a divided Congress for the first time Mr Trump also called on Washington to govern "not as two parties, but as one nation".
He began his State of the Union speech by saying there was a "new opportunity in American politics" and that "victory is not winning for our party, victory is winning for our country".
He added that "the only thing that can stop it are foolish wars, politics or ridiculous partisan investigations" – an apparent swipe at the special counsel probe into ties between Russia and the Trump campaign.
As he stood before politicians, the president was surrounded by symbols of his emboldened political opposition.
House Speaker Nancy Pelosi, who was praised by Democrats for her hard-line negotiating during the shutdown, sat behind Mr Trump as he spoke and House Democratic women created a sea of white, donning the colour favoured by early 20th-century suffragettes.
Mr Trump also defended his decisions to withdraw US troops from Syria and Afghanistan.
"Great nations do not fight endless wars," he said, adding that the US was working with allies to "destroy the remnants" of the Islamic State group and that he had "accelerated" efforts to reach a settlement in Afghanistan.
