What can be done to deflect North Korea's nuclear ambitions?

North Korea has restarted its plutonium production, according to US intelligence chief James Clapper, representing another milestone in its nuclear weapons program.

The assessment, outlined during the annual Worldwide Threat Assessment of the US Intelligence Community, comes just two days after Pyongyang launched a long-range rocket and little more than a month after its fourth nuclear test.

Why is North Korea pursuing this path, and can anything be done to divert it?

“Although North Korea issues official statements that include its justification for building nuclear weapons and threats to use them as a defensive or retaliatory measure, we do not know the details of Pyongyang’s nuclear doctrine or employment concepts,” writes Mr. Clapper, in the report to the Senate Armed Services Committee.

“We have long assessed that Pyongyang’s nuclear capabilities are intended for deterrence, international prestige, and coercive diplomacy.”

North Korea insisted its rocket launch on Sunday was for peaceful purposes. Others, including the United States, France, Japan and South Korea begged to differ, assessing instead that it was the test of a ballistic missile, capable of delivering nuclear warheads.

In fact, the United Nations Security Council convened an emergency session and released a response the very same day:

“Following emergency consultations today, the United Nations Security Council strongly condemned the missile launched by the Democratic People's Republic of Korea (DPRK), and announced that it will “expeditiously” adopt a new resolution in response to “these dangerous and serious violations.”

Even China expressed disapproval.

But, as noted in The Telegraph, this represented “an almost ritualistic denunciation," little more than “water off a duck’s back to the leadership in Pyongyang."

“Over the years, the UN has condemned the regime that runs the world’s most insular nation but that has not made the slightest difference to North Korea’s nuclear ambitions. It is apparent that being repeatedly told it has breached non-proliferation treaties, which it does not recognize, is a pointless exercise.”

In a similar vein, six-nation talks aimed at thwarting North Korea’s nuclear ambitions, involving South Korea, China, Japan, Russia and the United States, have been on hold since 2009.

Experts generally seem to agree there is only one thing, one entity, that can stop North Korea from bowling along the nuclear path: China. But even that emerging behemoth struggles to rein in its rambunctious neighbor.

“It is embarrassing for it [China] to have so little influence over the actions of its smaller neighbor,” notes The Economist.

But China is walking something of a tightrope. It harbors deep-seated fears of what might happen should the regime to its south collapse, risking floods of North Korean refugees pouring over its border and the disintegration of a useful buffer separating it from the US ally, South Korea.

And this brings us to the heart of what drives Pyongyang to continue blustering down this road, developing more nuclear weapons and desperately seeking ways of delivering destruction further afield: “the strategic calculus of the regime of Kim Jong-un that nuclear weapons are the ultimate guarantee of its survival."

Yet there is a line, over which even China is unlikely to allow North Korea to stumble – assuming, that is, that China does indeed have the ability to control Pyongyang. Such a line might be an act so outrageous as to warrant a blistering military response from Japan and the United States.

There is also the gathering momentum behind a missile defense system to shield South Korea from its northern counterpart, something China would regard as a threat to its own capabilities.

“The United States remains fully committed to the security of our allies in the region and we will take all necessary steps to defend ourselves and our allies and respond to North Korean provocations,” said Pentagon press secretary Peter Cook in a briefing Monday.

“To that end, and in response to the evolving threat posed by North Korea, the United States and the Republic of Korea have made an alliance decision to begin formal consultations regarding improvements to the alliance missile defense posture.  Specifically, the viability of a Terminal High-Altitude Area Defense, or a THAAD system, operated by US Forces Korea.”

Whether such a development might spur renewed efforts on the part of China to change the approach of Kim Jong-un’s regime is hard to predict, but it is unlikely the giant Communist power will sit idly by while the United States installs advanced missile defense technology in its backyard.

Moreover, some people have not yet given up on the power of dialogue and diplomatic engagement.

“Neighbors in Asia face the most urgent threat, but as North Korea improves its nuclear and missile arsenals, the threat will rapidly become global,” states the bulletin of the Atomic Scientists’ annual Doomsday Clock Statement.

“Now is not the time to tighten North Korea’s isolation, but to engage seriously in dialogue.”