Special articles and reports on timely nonproliferation issues by CNS staff.

Updated: Apr 27, 2012

FAQ: North Korea's Possible Nuclear Test

Recent rhetoric coming from Pyongyang combined with a number of indicators visible on satellite images indicates that North Korea is preparing for its third nuclear test. CNS experts have prepared this FAQ about the possible test and its potential international ramifications.

1. Why is North Korea preparing to conduct a nuclear test?

If North Korea conducts a nuclear test, it will probably have more political than scientific value. What North Korea is preparing to do is better described as a "demonstration" rather than a "test." Pyongyang reacted to the United Nations Security Council's (UNSCR) condemnation of North Korea's recent rocket launch by calling it an attempt to "deride and encroach upon the dignity of the nation and the sovereignty of the country." In 2006 and 2009, North Korea responded to similar condemnations of rocket launches with similar rhetoric, culminating in nuclear tests. Most observers expect that pattern to repeat. The failure of that missile test may also put pressure on the new young leader of North Korea, Kim Jong Un, to prove his strength and ensure support from more conservative factions inside the governing regime . A nuclear test may fit that bill.

2. When will the test take place?

A test could occur at any time. North Korea has announced that it is no longer bound by the moratorium on nuclear testing and is "able to take necessary retaliatory measures, free from the agreement." Reuters quoted a "senior source with close ties to Pyongyang and Beijing," as saying the test could be "soon."

The main physical indicator of preparations for an underground nuclear explosion is the digging (and capping) of a tunnel for the nuclear explosive. Satellite imagery from early April 2012 shows activity at the test site, in particular a now larger pile of earth from tunneling efforts. Tunneling is suggestive, but not definitive – North Korea began digging the same tunnel in 2010.

3. Where is North Korea's test site?

North Korea's nuclear test site is located approximately 15 km northwest of the village of Punggye, in Gilju-gun, North Hamgyeong Province (함경북도 길주군 풍계리). Satellite imagery from March 24, 2012, showed a growing pile of earth near an "adit" (tunnel entrance) at 41°16'35.00"N, 129° 5'16.41"E. The South Korean press calls this the "south entrance."

Other possible adits are visible to the east and north of the support buildings at 41°16'47.18"N, 129° 5'54.79"E and 41°16'50.09"N, 129° 5'8.24"E. These may be entrances to the tunnels North Korea used to conduct tests in 2006 and 2009.

5. Will North Korea use Uranium or Plutonium for the device it tests?

North Korea's first two tests likely used plutonium devices. In November 2010, North Korea confirmed long-standing US suspicions that it was pursuing a covert uranium enrichment program by revealing a uranium enrichment facility that it constructed after April 2009 at its Yongbyon nuclear site to Stanford Professor Siegfried Hecker.

One possibility is that North Korea will attempt to test a device using highly enriched uranium, both to validate a new design and to conserve its limited stockpile of plutonium. On the other hand, there is no firm evidence that North Korea has produced enough highly-enriched uranium, either at Yongbyon or elsewhere, for a nuclear device.

Outside observers may not be able to immediately determine what type of device North Korea tests. Although the 2006 test "vented" radioactive material into the atmosphere, allowing the U.S. to confirm the explosion was fueled with plutonium, the 2009 test did not release any detectable material.

6. How many nuclear tests has North Korea conducted?

As noted above, North Korea has conducted two nuclear weapons tests at the same site.[1] KCNA, North Korea's state media, announced both tests.

The first occurred underground on October 9, 2006 at 10:35 am local time. Air samples confirmed the test, and the U.S. Office of the Director of National Intelligence (ODNI) estimated the yield to be less than one kiloton using plutonium from North Korea's 5MW reactor at Yongbyon. The second occurred on May 25, 2009 at 9:54 am local time approximately. The underground explosions occurred to the North of the test site, about 2.5 km apart from each other. Although no radioactive materials were detected from the second event, the United States intelligence community concluded the event was a "probable nuclear test" with a yield of approximately 2 kilotons that was apparently more successful than the 2006 test.

7. What does a nuclear test mean for the United States and regional allies, like South Korea and Japan?

Although North Korea has probably been disappointed in the yields of its two nuclear explosions, even a "small" nuclear explosion in a city would be enormously destructive and incite panic. The 2009 DPRK nuclear test, with a yield of two kilotons, had only about 1/10 the explosive power of the atomic bomb that destroyed Nagasaki (21 kt), but was 1,000 times more powerful than the truck bomb made from fertilizer and diesel fuel used in the attack on the Alfred P. Murrah Federal Building in Oklahoma City (2,000 kilograms or ~.002 kt).

Additional weapons testing may help North Korea reduce the size of its nuclear weapons so that they are small enough to place on a ballistic missile or improve their reliability. Nuclear-armed North Korean missiles could threaten urban areas in South Korea and Japan. If North Korea were to test a device using highly enriched uranium, it would open up a new route to nuclear weapons development for Pyongyang.

8. Why can't China stop North Korea from conducting this test?

Chinese officials have made clear for years that although China and North Korea have relatively good relations, China will not risk creating a war or instability on the Korean peninsula over North Korea's nuclear program. For its part North Korea has long worried about becoming a puppet state of China and has issued veiled threats to Beijing not to undermine the stability of the DPRK. In short, although China probably has the leverage to make North Korea do what it wants, it is not prepared to do so for fear that North Korea might collapse. Such a collapse, China fears, could spark a war on its border, lead to a flood of millions of North Korean refugees coming across its border, and ultimately bring U.S. and South Korean troops in a reunified Korea right up to the Chinese border.

9. What does this test mean for the Comprehensive Test Ban Treaty (CTBT)?

North Korea is one of the 44 states that must sign and ratify the CTBT for it to enter-into-force. Any nuclear explosion is, of course, inconsistent with the aim of the treaty to eliminate nuclear tests in order to prevent the further spread of nuclear weapons, promote disarmament and enhance international peace and security. North Korea has not signed or ratified the CTBT and is not bound by its obligations.

The Comprehensive Test Ban Treaty Organization's International Monitoring System (IMS) detected both of North Korea's previous tests, even though both explosions were significantly smaller than the system was designed to detect. In general, the experience with North Korean testing has demonstrated that the IMS provides a significant ability to verify the CTBT. (The United States has a separate, classified network operated by the Air Force Technical Applications Center known as the United States Atomic Energy Detection System.)

Note

[1] A small number of observers speculate that North Korea conducted additional unannounced nuclear tests in May 2010. This appears to be a minority view not shared by the United States or other governments, based in part on the lack of seismic activity at the time.