North Korea is not planning any missile or nuclear tests, the country's ambassador to the UN in Geneva, So Se Pyong, has told Reuters news agency.
Mr So was also quoted as saying that North Korea was ready to resume six-party talks on its nuclear programme.
North Korea has been conducting missile and nuclear tests since the negotiations broke down in 2008.
The envoy also dismissed as "fabricated rumours" recent reports that North Korean leader Kim Jong-un is unwell.
Mr Kim has not been seen in public for four weeks, and missed an important political meeting in late September.
A state TV report said he was suffering from an "uncomfortable physical condition".
In the interview with Reuters, Mr So rejected the suggestion that his country was planning further missile tests.
However, he appeared to suggest that North Korea's policy was a response to US and South Korean exercises earlier this year.
"We have to be alert also, we have to be prepared to make counter measures against that military exercise which are against us," he was quoted as saying.
"In case, in case, if they do that kind of joint military exercise, the joint nuclear military exercise against my country continuously, we have to, also."
North Korea pledged to abandon its nuclear programme in 2005, but appeared to backtrack by testing devices in 2006 and 2009.
The programme was the subject of six-nation talks, involving Russia, China, Japan, the US and North and South Korea, until 2009.
Attempts to restart the negotiations have floundered.
"For the six-party talks we are ready," Mr So told Reuters, adding that Russia and China were also prepared.
"But America, they don't like that kind of talks right now," he was quoted as saying. "Because America does not like that, so that's why the countries like South Korea, Japan also are not ready for those talks."
Mr So also told Reuters his country's nuclear programme had acted as a deterrent against the US.
"In case if we give [the weapons] up like other countries, then of course I think they would have attacked us already," he was quoted as saying.
Mr So said he was unaware of US efforts to secure the release of three American citizens held in North Korea on charges of crimes against the state.
"I don't know whether America is ready or not to release them or have some understandings or the recognition of those crimes they made," he said.
A US official has accused North Korea of missing an opportunity to build relations with the US by refusing to discuss the detentions.