The launch followed a fresh round of UN sanctions and was unanimously condemned by the UN Security Council as "highly provocative".
What has North Korea said?
The foreign ministry statement, carried by the country's official news agency KCNA, said: "The increased moves of the US and its vassal forces to impose sanctions and pressure on the DPRK [Democratic People's Republic of Korea] will only increase our pace towards the ultimate completion of the state nuclear force."
It also said that the goal of the new UN sanctions, approved on 11 September, was to "physically exterminate" the country's people, system and government.
The issue of North Korea's weapons programme is expected to dominate US President Donald Trump's address at the UN General Assembly and his meetings with the leaders of South Korea and Japan.
Mr Trump previously warned that "all options" were on the table and that North Korea would face "fire and fury" if it continued to threaten the US.
In a phone call on Monday, Mr Trump and Chinese President Xi Jinping committed to "maximising pressure on North Korea through vigorous enforcement" of UN Security Council resolutions, the White House said.