On March 10, Lt. Gen. Ronald Burgess, director of the Defense Intelligence Agency, testified that North Korea “may now have several plutonium-based nuclear warheads that it can deliver by ballistic missiles and aircraft as well as unconventional means.” It is uncertain whether Lt. General Burgess’s statement is based on new intelligence reporting or a higher level of confidence that DIA has in the new analytic assessment.

His remarks were disturbing because most experts to date have held that North Korea has not yet mastered the requirements to miniaturize any nuclear warhead sufficiently to put it on a missile.

Director of National Intelligence James Clapper, testifying concurrently with Burgess, stated only that “although we judge North Korea has tested two nuclear devices, we do not know whether the North has produced nuclear weapons, but we assess it has the capability to do so.”

Either assessment is troubling enough that policymakers should be looking at ways to increase the pressure on Pyongyang.

As I commented last week in testimony before the House Foreign Affairs Committee, “North Korea poses a multi-faceted military threat to peace and stability in Asia as well as a global proliferation risk.” In addition to possessing enough plutonium for six to eight nuclear weapons, North Korea disclosed last November a previously unknown uranium-enrichment facility. This validated earlier U.S. assertions that Pyongyang was also pursuing a parallel uranium-based nuclear weapons program. North Korean officials have repeatedly vowed that the regime has no intention of abandoning its nuclear arsenal.

Secretary of Defense Robert Gates announced in January that “North Korea is becoming a direct threat to the United States” since it will develop an intercontinental ballistic missile within five years. Although the media depicted Gates’s comments as a major “new assessment,” North Korea’s expanding missile threat to the United States and its allies has been long known. The U.S. National Intelligence Community warned in a 2001 National Intelligence Estimate that “before 2015 the United States most likely will face ICBM threats from North Korea and Iran.”

The Defense Department’s U.S. Ballistic Missile Defense Review warned in February that the global ballistic-missile threat is “increasing both quantitatively and qualitatively, and is likely to continue to do so over the next decade . . . ballistic missile systems are becoming more flexible, mobile, survivable, reliable, and accurate, while also increasing in range.”

North Korea’s inability thus far to achieve its diplomatic objectives through provocations will eventually compel it to engage in more high-risk confrontational measures, even as it appeals for negotiations with the United States. The next provocation could be tactical military confrontations along the Demilitarized Zone and Northern Limit Line, another nuclear test, or a long-range missile launch.

Pyongyang probably calculates that demonstrating enhanced missile capabilities could be used as leverage against Washington and Seoul, forcing them to abandon their current pressure tactics against Kim’s regime.

The United States should continue its current, two-track policy of pressure and conditional engagement, but with additional measures. Overall, it is a good strategy, but has been weakly implemented by the Obama administration.

Since international diplomacy and U.N. resolutions did not prevent North Korea from continuing its development and testing of nuclear weapons and ICBM delivery capabilities, the U.S. and its allies should develop and deploy sufficient missile defenses.

Unfortunately, while the North’s threat has grown, the level of preparation on the part of Washington and its allies has dwindled.

During the past decade, Japan has made considerable strides in ballistic-missile defense. Tokyo has developed and deployed a layered integrated missile-defense system consisting of Aegis destroyers with Standard Missile-3 interceptors and land-based Patriot Advance Capability-3 missiles.

But Japan’s missile defenses are handicapped, thanks to legal restrictions against “collective self-defense” or defending another country against attack. So despite its technological advantage, Tokyo would not be allowed to intercept missiles attacking the United States or to protect a U.S. naval vessel that was defending Japan from missile attack — even if it were adjacent to a Japanese Aegis destroyer.

In South Korea, liberal administrations have for ten years downplayed the danger of North Korean missiles to garner domestic support for Seoul’s attempts to foster reconciliation with Pyongyang. Successive presidents were also fearful that deploying a missile-defense system would anger Pyongyang, lead to a collapse of the inter-Korean engagement policy, and strain relations with China. So it was pretty much a lost decade in terms of missile-defense preparation.

South Korea has been more receptive to the idea of building missile defenses since the 2008 election of President Lee Myung-bak. But Seoul has yet to follow through with actions. Most notably, South Korea continues to resist joining a comprehensive regional missile-defense network with the U.S. and Japan.

The U.S. and its allies need to move forward on missile defense for Asia. But the disasters in Japan and the focus on recovery there will render progress in this area difficult for a while. In the meantime, North Korea will continue its drive toward becoming a nuclear powerhouse.

Bruce Klingner is former chief of the CIA’s Korea branch and a senior research fellow at the Heritage Foundation’s Asian Studies Center.