North Korea has said it has turned plutonium from 8,000 spent fuel rods into nuclear weapons.
Mr Choe blamed the nuclear impasse on Washington
Speaking at the UN General Assembly, Vice Foreign Minister Choe Su-hon said the weapons were needed for "self-defence" against "US nuclear threat".
Pyongyang has said before that it had reprocessed the rods, but has not been specific about how the material was subsequently used.
Seoul has estimated that 8,000 rods is enough for up to eight weapons.
In his speech to the General Assembly, Mr Choe again blamed the US' "hostile policy" for the nuclear stand-off.
He was then asked in a news conference afterwards what the North Korean nuclear deterrent entailed.
"We have already made clear that we have already reprocessed 8,000 wasted fuel rods and transformed them into arms," he said.
Asked if the fuel had been turned into actual weapons, he replied "We declared that we weaponised this."
Pyongyang is also known to have missiles, and in recent days US and South Korean intelligence has picked up signs a missile test may be planned.
But Mr Choe, in an interview with Chinese state news agency Xinhua, denied this as "nothing but rumours".
Six-nation talks on the nuclear issue, which were due to have resumed before the end of September, have been put on hold since Pyongyang made clear its dissatisfaction with Washington's stance.
Analysts believe North Korea has ruled out further progress until after the US presidential election in November.
The North did, however, take part in talks with Japan over the weekend which focused on missing Japanese which North Korea is believed to have kidnapped, but Japanese officials said they were disappointed that Pyongyang did not release more details.
"We don't think that was enough," Chief Cabinet Secretary Hiroyuki Hosoda told reporters on Monday.
"It's important for North Korea to provide more detailed reports soon."