North Korea has said it will "physically display" its nuclear deterrent, according to the North Korean news agency KCNA.
North Korea restarted its Yongbyon nuclear reactor last year
It was not immediately clear what prompted the claim, but it appeared to be the latest in a series of aggressive statements regarding Pyongyang's nuclear programme.
The threat comes a day before US President George W Bush is set to arrive in Japan as part of an Asian tour in which North Korea's nuclear ambitions are likely to feature heavily.
"When the time comes a measure will be taken to physically disclose the nuclear deterrent," a North Korea foreign ministry spokesman told KCNA, as monitored by South Korea's Yonhap news agency.
He said that would end speculation over whether North Korea was in possession of a nuclear weapons force.
Earlier this month, North Korea said it was in possession of a nuclear deterrent and was working to strengthen it, although Western intelligence agencies are unsure whether the claims are a bluff.
And according to the US, Pyongyang threatened in August to test a nuclear weapon.
North Korea often tries to use brinkmanship to extract aid or other concessions from its negotiating partners.
An international talks process is under way over North Korea's nuclear programme.
The US wants North Korea to dismantle it, but Pyongyang says it wants a non-aggression treaty, economic aid, and diplomatic relations first.
Six-party talks were held on the issue in Beijing in August, although Pyongyang has subsequently said it is not interested in further negotiation.
It is very difficult to verify North Korea's claims about its nuclear programme, because Pyongyang expelled UN inspectors from the country last year.
It subsequently restarted its nuclear reactor at Yongbyon, which some analysts believe is capable of generating enough plutonium for about one weapon per year.
In addition, North Korea earlier this month said it had reprocessed 8,000 spent nuclear rods.
The CIA believes these are enough to produce a small number of nuclear bombs.