NORTH Korea's progress on nuclear weapons and long-range missiles is 'a harbinger of a dark future' and has created an urgent need for more pressure on the reclusive communist government to change its ways, US Defence Secretary Robert Gates said at the Shangri-La Dialogue.

The North's nuclear program does not 'at this point' represent a direct military threat to the United States and he does not plan to build up American troops in the region, Gates said Saturday. But the North's efforts pose the potential for an arms race in Asia that could spread beyond the region, he added.

At an annual meeting of defence and security officials, the Pentagon chief said past efforts to cajole North Korea into scrapping its nuclear weapons program have only emboldened it.

North Korea's yearslong use of scare tactics as a bargaining chip to secure aid and other concessions - only to later renege on promises - has worn thin the patience of five nations negotiating with the North, Gates said.

'As the expression goes in the United States, 'I am tired of buying the same horse twice.' I think this notion that we buy our way back to the status quo ante is an approach that I personally at least think we ought to think very hard about. There are perhaps other ways to try and get the North Koreans to change their approach,' he said.

The sharp statements were echoed by the South Korean defence minister and even China, North Korea's strongest ally. They reflect fears throughout the region that last week's nuclear and missile tests by North Korea could spiral out of control and lead to fighting.

The North said it would no longer honour a 1953 armistice truce with South Korea after Seoul joined a 90-plus nation security alliance that seeks to curb nuclear trafficking on the seas.

Additionally, the UN Security Council is drafting financial and military penalties against North Korea as punishment for the weapons testing. Similar penalties approved after the North's 2006 atomic test have been only sporadically enforced, and largely ignored by China and Russia.

Later, at what officials called the first-ever meeting among defence chiefs from the US, Japan and South Korea, Gates asked his counterparts to begin considering other steps against the North should it continue to escalate its nuclear program. The military leaders did not discuss specific potential actions, but US officials who attended the half-hour meeting said any steps would be taken in self-defence.

Earlier Saturday, Lt Gen. Ma Xiaotian, the second-in-command of the General Staff of China's military, told the security forum that Beijing 'has expressed a firm opposition and grave concern about the nuclear test.' The Obama administration said it planned to send a delegation on Sunday to Tokyo, Seoul, Beijing and possibly Moscow to discuss how to respond to North Korea. -- AP