A nuclear weapons test by North Korea would reverberate around the world, altering the nuclear balance in Asia and posing stark new challenges for US policy-makers and military planners.
It could also induce China, Russia and other powers to join the US in seeking UN-approved penalties against the hard-line communist country, analysts suggest.
With US officials increasingly concerned that North Korea may conduct a test soon, how would Washington respond?
First, the Bush administration probably would try to involve the UN. Less clear is whether US President George W. Bush would consider a risky military strike -- given North Korean leader Kim Jong-il's million-man army, heavy conventional weaponry and perhaps several nuclear weapons.
"The North Koreans are basically hellbent on proving to the world that they need to be taken seriously. That's dangerous," said Representative Curt Weldon, vice chairman of the House Armed Services Committee.
"A North Korean test would embarrass China and might actually rally other nations to our position. But the result might push Kim Jong-il to take whatever steps he felt were necessary to rally his people into war," Weldon said.
Weldon, who led a delegation to North Korea in January, said he met last Monday in New York with North Korea's deputy UN ambassador, Han Song-ryol, and told him, "If you do a test, you're going to set this process back years and years, and it's going to lead to consequences neither of us want."
Meanwhile, North Korea has indicated a willingness to return to the bargaining table but said it is waiting for Washington to clarify conflicting statements on US policy. Citing differences between Washington's public and private statements, the North's official Korean Central News Agency quoted a Foreign Ministry spokesman Sunday as saying Pyongyang "will continue to closely watch the US side's attitude, and when the time comes we will officially deliver to the US side our position through the New York contacts."
White House press secretary Scott McClellan said Monday that the Bush administration sees no contradictions in its statements on North Korea.
"The six-party talks are the way forward to resolving this issue. We want to see them come back to the talks. We have no preconditions for returning to the talks and we've made that very clear," he said.
US officials want China to exert more pressure on its longtime ally. China says bullying rhetoric by the US makes it harder to coax the North Koreans back to the negotiating table.
"The potential downside of a test is enormous," said Kurt Campbell, former assistant secretary of defense for Asia in the Clinton administration. "It would set off a chain reaction in the region with completely impossible-to-predict consequences."
It could even lead South Korea and Japan to rethink their policy against nuclear arsenals, he said.