0323 GMT July 21, 2018
"Our principal position is that we will never agree to any talks in which our nuclear weapons will be the subject of negotiations,” Ri told Russia's TASS news agency on Wednesday.
North Korea and the United States have locked horns in recent weeks over Pyongyang's nuclear weapons and missile programs.
North Korea has test-fired several missiles. Last month, it tested a powerful hydrogen bomb that could be loaded onto an intercontinental ballistic missile (ICBM).
Following the test, there has been an escalating war of words between the two countries.
In a bellicose first address to the UN General Assembly, US President Donald Trump described North Korea as a rouge country and threatened to totally destroy it.
The North Korean foreign minister said Trump had "lit the wick of a war" with his country, adding, "We need to settle the final score, only with a hail of fire, not words."
Ri also said that North Korea had achieved a “real balance of power with the United States.”
Amid heightened tensions, the US conducted a joint military exercise with South Korea late on Tuesday, flying two strategic bombers over the Korean Peninsula.
The US said Japan's Air Force also took part in the drill.
It was he first time US bombers conducted training with fighters from both Japan and South Korea at night.
Meanwhile, US Secretary of Defense James Mattis said on Monday diplomacy along with economic sanctions against Pyongyang would remain the leading element of US strategy towards North Korea. He, however, added that the military would continue to prepare options should diplomacy fail.