It comes a day before North Korean leader Kim Jong-un holds historic talks with US President Donald Trump.
The comments are a marked shift in tone from the isolated country after decades of animosity towards the US.
Both leaders arrived in Singapore on Sunday evening. Mr Trump has said he has a "good feeling" about their much-anticipated summit.
He tweeted on Monday morning that there was "excitement in the air" in Singapore.
The US president, who flew in on board Air Force One, hopes the summit will kick-start a process that eventually sees Mr Kim give up nuclear weapons.
They are staying in separate hotels, not far from each other, and will meet on Tuesday at a hotel on Sentosa, a popular tourist island a few hundred metres off the Singapore mainland.