A new UN report documents that Iran is working with North Korea in developing ballistic missile technology. Specifically, the report finds that the two nations are transferring prohibited “ballistic missile-related items” via air shipments, in direct violation of UN sanctions.

Want to read more about it? Sorry, you can’t. China is blocking release of the report.

China has a history of bottling up inconvenient reports, and it’s little wonder they worked to squash this one. According to leaked passages, the illicit transfers involved “trans-shipment through a neighboring third country.” Several UN diplomats said that this country was China.

Earlier this year, China blocked publication of another damning UN report which said the North almost certainly has more undisclosed enrichment-related facilities. It went on to voice concerns that North Korea might “transfer fissile materials or the means of producing them” to foreign countries — such as Iran.

Iranian delegations have visited North Korea in the past to observe missile tests and exchange technology. This newest UN report, buried by China, affirms U.S. concerns about Chinese willingness to look the other way when it comes to North Korean nuclear activities. Diplomatic cables published through WikiLeaks show that the U.S. has repeatedly importuned Beijing to bar North Korean shipments through China, yet China has taken no action.

North Korea and Iran have a long history of military, economic and intelligence cooperation. Their collaboration on missile technology goes back to the Iran-Iraq war. In fact, Tehran’s ballistic missile inventory, the largest in the Middle East, is largely based on North Korean missile designs.

In testimony earlier this year, James Clapper, director of national intelligence, highlighted North Korea’s ballistic missile proliferation activities regarding Iran and hinted that this cooperation is bearing dangerous fruit. Tehran continues to “expand the scale, reach and sophistication of its ballistic missile forces, many of which are inherently capable of carrying a nuclear payload,” Clapper said.

Iran is investing heavily in ballistic missile, nuclear, and space programs — all run by the military. Unfortunately, it is making impressive strides on all fronts. Tehran’s new two-stage solid-propellant missile may soon be able to reach Eastern Europe and U.S./NATO bases, enabling it to hold governments hostage simply by threatening to launch its missiles.

North Korea also has an extensive ballistic missile force and is making steady progress in increasing range, payload and accuracy. Lt. Gen. Ronald Burgess, director of the Defense Intelligence Agency, testified earlier this year 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.”

Burgess’ remarks were surprising because most experts feel North Korea has not yet mastered the technology needed to make nuclear warheads small enough to mount on a missile. There is even debate as to whether Pyongyang has weaponized its fissile material. DNI head 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.”

Last week, Raymond Colston, the new national intelligence manager for Korea at the National Intelligence Director’s Office, reiterated a point made earlier this year by Defense Secretary Robert Gates. North Korea, Colston said, is “certainly building missiles that eventually will be capable of targeting the U.S., and these missiles will be capable of having nuclear weapons.”

While the extent of cooperation on nuclear weapons technology is murky, North Korea has already threatened to transfer nuclear weapons. Michael Green, former senior director for Asia at the National Security Council, says that, during nuclear talks in March 2003, the head of the North Korean delegation confirmed that Pyongyang had a “nuclear deterrent” and threatened to “expand,” “demonstrate,” and “transfer” the deterrent unless the United States ended its hostile policy.

The bottom line is that neither U.S. engagement nor UN sanctions have deterred Iran and North Korea from pressing forward on the ballistic missile and nuclear front. The U.S. intelligence community has long warned of the ballistic missile threat from these two nations. Amidst this ever-growing threat, President Obama’s approach to missile defense is misguided.

After the large-scale cuts to missile defense made in fiscal year 2010, President Obama’s proposed budgets for FY 2011 and FY 2012 simply don’t make up the lost ground. Apparently he believes in “just-enough” and “just-in-time” missile defense. The problem with this approach is that it leaves the U.S. wildly vulnerable to missile attack should the more comforting intelligence predictions prove wrong. History shows that our enemies have no hesitation about using an unexpected breakout capability.

James Jay Carafano is director of The Heritage Foundation’s Allison Center for Foreign Policy Studies, where Owen Graham is research coordinator for national security and foreign policy.