As North Korea threatens additional missile tests following its nuclear test in late May and April rocket launch, nuclear experts at the Belfer Center offer analysis and commentary on North Korea's actions and intentions and what the Obama administration should do now.

Hui Zhang's article "The North Korean Nuclear Test: The Chinese Reaction" was published by the Bulletin of the Atomic Scientists.  In his article, Zhang argues that like South Korea, Japan, and the United States, China quickly rebuked North Korea for its nuclear test last week.  However, despite growing frustration with Pyongyang, China will more than likely continue to oppose harsh U.N. sanctions against North Korea, and finally, China probably will use its leverage on North Korea only when Washington makes Pyongyang a serious offer that includes normalization of relations and robust security guarantees.

"To facilitate enhanced Chinese support for North Korean denuclearization, Washington should also address some of Beijing's security concerns, including US-Japanese missile defense cooperation and sales of missile defense capabilities to Taiwan. The United States and China could also offer one another specific assurances regarding military deployments on the Korean peninsula. Even in the event of a North Korean collapse, the United States has no intention of moving its forces to the Chinese border; it would reduce Beijing's concerns if Washington said so."

Hui Zhang presented "China's Nuclear Fuel Cycle: A Case Study of FMCT Verification" at the SIPRI Seminar, Verifying a Fissile Material Cut-off Treaty: Technical Issues and Political Choices, UNDIR, Palais des Nations, Geneva, on May 25, 2009.

Hui Zhang's Op-Ed in the Boston Globe argues that negotiations with North Korea must resume immediately on denuclearization, or there is a risk that North Korea may conduct further tests on its long-range missiles or even another nuclear explosion.

Hui Zhang writes in a Nautilus Institute Policy Forum Online Op-Ed that despite North Korea's recent missile test, "Each side should take reciprocal actions to show their good-faith commitment to the North Korean denuclearization...From China's perspective, the first step should be taken by the side with the least to lose. This is not North Korea...Washington should take the first step that will eventually lead to North Korean denuclearisation."

Hui Zhang argues that an effective universal Fissile Material Cutoff Treaty (FMCT) would make an important contribution to nuclear disarmament, the nonproliferation regime, and the prevention of nuclear terrorism. However, such a FMCT must have a credible verification regime. Dr. Zhang suggests that it should be technically feasible to establish an effectively verifiable FMCT at a reasonable cost, while protecting national security secrets.

The American Academy of Arts and Sciences called upon Pavel Podvig and Hui Zhang to consider what consequences would develop if the United States continues to pursue the weaponization of space and how China and Russia would respond, and what would be the broader implications for international security.

In this paper, Zhang explores what information could have been obtained from offsite air sampling analysis. Specifically, he examines how to use the activity ratios of xenon isotopes to identify the North Korean nuclear test and whether the off-site air sampling analysis would be able to distinguish a test from a plutonium-bomb and a HEU bomb.

In this paper, Zhang examined if the test was successful. Based on a technical analysis, Zhang concluded that: whether North Korea’s Oct. 9 nuclear test was successful or failed would be dependent on North Korea’s designed yield. If North Korea planned a yield of 4 kt (as told to China), it would be not a failed test. It could show that North Korea already had confidence to explode a nuclear device and pursued a much more compact warhead for its missiles. Thus, it is urgent to negotiate for dismantling North Korean nuclear and long-range missile programs.