North Korea said Sunday it would never trade its nuclear weapons programme for aid and stressed its "unshakeable" stance to retain the deterrent, following a third atomic test last month.
The North's foreign ministry, in a statement carried by state TV, rejected suggestions that the impoverished state was using its weapons programme as a way of bullying neighbours into offering much-needed aid.
"The US is seriously mistaken if it thinks that the (North) had access to nukes as a bargaining chip to barter them for what it called economic reward," it said.
The comments came days after the US National Security Advisor Tom Donilon said Washington was willing to hold "authentic negotiations" with the North if it changed its behaviour.
"To get the assistance it desperately needs and the respect it claims it wants, North Korea will have to change course," he said last week.
But the North Sunday called its atomic weaponry a "treasured sword" to protect itself from what it called a hostile US policy.
The US "temptation" may work on other countries "but it sounds nonsensical" to the North, the foreign ministry statement said.
"The (North) would like to re-clarify its unshakeable principled stand on its nuclear deterrence for self-defence."
Last month's test, its most powerful to date, prompted the United Nations to further tighten sanctions imposed following previous nuclear tests and long-range rocket launches in 2006 and 2009.
The tougher sanctions, and an ongoing South Korean-US military exercise, sparked an angry response from Pyongyang, which said it was tearing up the armistice that ended the Korean War and ending non-aggression pacts with Seoul.
The country has suffered chronic food and fuel shortages for decades, with the situation exacerbated by floods, droughts, mismanagement and global sanctions.
International food aid, especially from South Korea and the US, has been drastically cut over the past several years amid tensions over the North's nuclear and missile programmes.
A six-nation aid-for-denuclearisation forum on the North, involving the two Koreas, China, Japan, the US and Russia, have been at a standstill since the last meeting in December 2008.
Almost 28 percent of the North's children aged under five are stunted from malnutrition, a 2012 UN national nutrition survey showed.