WASHINGTON, May 29 (Reuters) - North Korea's second nuclear test has forced the United States to grapple with the idea that Pyongyang may never give up atomic weapons, current and former U.S. officials said this week.

The potential implications range from a higher risk of global weapons proliferation, to an atomic arms race in the region, to a direct threat to U.S. allies South Korea and Japan.

"This is a whole new ballgame and it's a whole lot deeper and darker and scarier," said a U.S. official who spoke on condition he not be identified.

"It's a bit like when you get out a pair of binoculars and you get it just right. It has brought into crystalline focus what North Korea's intentions are -- that they do mean to develop this capability," he added. "It changes, or it should change, people's calculus about how to deal with this."

North Korea detonated a nuclear device this week for only the second time in its history; it fired short-range missiles; and it said Seoul joining a U.S. counter-proliferation effort that could lead to inspections of North Korean ships had invalidated the armistice that ended the 1950-53 Korean War.

Historically the impoverished, authoritarian state has used such steps as chips to drive a harder bargain in its negotiations with the West. That may no longer be the case.

"In the past, there was the long lead time and it was 'Please stop me before I do this provocation and you can do so by paying me off,'" said Bruce Klingner, a former CIA analyst now with the Heritage Foundation think tank in Washington.

"Now, they're doing it so quickly that there's no way you can intervene diplomatically," he added. "It's as if they've abandoned the facade of diplomacy and negotiations -- at least until they achieve a viable nuke and ICBM."

COERCIVE DIPLOMACY?

William Perry, a former U.S. defense secretary who played a role in a 1994 U.S.-North Korean deal under which Pyongyang froze its nuclear program in exchange for aid, said the old pattern may no longer hold and that Washington may need to adopt a tougher line.

"I do believe that diplomacy still has a chance of success, but only if is robust and only if the robustness includes some meaningful coercion components," Perry said at the Council on Foreign Relations think tank on Thursday.

The best way to squeeze the country's leadership may be through financial sanctions "with a real bite," he said, adding that if these fail the United States should consider other steps, including the possibility of military strikes.

Brent Scowcroft, a former White House national security adviser, argued that one silver lining to the test may be that it will help to enlist the Chinese in mitigating the risks from a nuclear-armed North Korea.

"We have never been able to figure out, in the over 15 years of negotiations we have had with North Korea, what their goals are. Is their goal to become a nuclear state or are nuclear weapons trading materials for a security regime in which North Korea would feel secure?" he said at a joint appearance with Perry at the Council on Foreign Relations.

"Now it looks like that is becoming clearer and they are deciding that their goal is (to be) a nuclear weapons state. I think that makes a big difference in the Chinese attitude," he added. "It seems to be clear to me that we have additional leverage and reason to get cooperation from our friends."

China, North Korea's dominant trading partner, is seen as the linchpin of any effort to contain a nuclear-armed Pyongyang but it is believed to be reluctant to push so hard that it might trigger the collapse of its neighbor.

Such a collapse could result in tens of thousands of North Korean refugees streaming into China.

In New York, the United States and Japan circulated a draft U.N. Security Council resolution that condemned Pyongyang's latest nuclear test and called for strict enforcement of U.N. sanctions imposed on North Korea after its first test in 2006.

"It is not just about the U.N. Security Council preserving face," said a U.S. official. "It's about really fundamental issues related to northeast Asian security, now." (Additional reporting by Paul Eckert, editing by Philip Barbara)