Because unlike your childhood playmates, North Korea knows no rules.
In retaliation for tightened U.N. sanctions following North Korea's May 25 nuclear test and subsequent missile tests, Pyongyang defiantly upped the ante on Saturday, June 13. North Korea said it will move forward with its plans to build a nuclear arsenal, begin a program of uranium enrichment, and take resolute military actions against the United States and its regional allies. Then on Thursday, June 18, news surfaced that the next missile test might be pointed toward Hawaii (the missiles in question don't have the range to actually reach the islands -- only head that way). Pyongyang is also reportedly preparing another nuclear test.
This game of escalation will go on and on until North Korea gets what it desires most from Washington: a reliable security assurance. Of course, no one likes to yield to dictators. But ultimately, playing chicken with a desperate and nuclear-armed North Korea is too risky to endeavor. The more isolated the North Koreans become, the more likely they will be to use the nuclear card in threatening two hostages: South Korea and Japan. Everyone loses that game.
With two nuclear tests under its belt, Pyongyang should have more confidence in its capability to mate its smaller and low-yield warheads (about 4 kilotons) with its existing Scud missiles (which are capable of reaching all of South Korea) and Nodong missiles (with the range to strike all of Japan, including the U.S. military bases there). A 4-kiloton bomb would not be as powerful as the 15 to 20 kilotons dropped on Hiroshima and Nagasaki, but it could cause greater casualties given the significantly higher population densities of South Korea and Japan today, especially in their capitals of Seoul and Tokyo. A 4-kiloton bomb could cause hundreds of thousands of deaths from the blast, burns, and ensuing radiation.
It gets worse. Pyongyang also said on Saturday that it had reprocessed more than one third of its newly discharged 8,000 spent fuel rods -- a claim that is likely true. Within another three months, North Korea could harvest between 8 and 12 kg of plutonium, or enough for one to two bombs. The country has also confirmed that it started a program to create highly enriched uranium (HEU). If North Korea were to successfully develop a centrifuge enrichment facility capable of producing one bomb's worth of HEU, it would pose a huge challenge to denuclearization. Unlike plutonium production, which involves large reactor facilities and generates a considerable amount of heat, the facility North Korea has in mind would be compact and thus easier to hide. Verification would require more-invasive inspections -- and the (unlikely) cooperation of Pyongyang.
Conveniently for North Korea, HEU is also much more attractive than plutonium to subnational groups in the market for nuclear weapons because HEU bombs are relatively easier to make. For an eager buyer, Pyongyang might become a willing supplier with the right situation and price. After all, North Korea has dabbled in selling missiles and missile technologies to Iran and others. North Korea reportedly helped Syria build a reactor that was destroyed by Israeli airstrikes in September 2007. The probability that any sane country would make such a nuclear transfer is extremely low, but an armed and desperate North Korea might do so in a last-ditch attempt to save the regime. From Pyongyang's perspective, what's not to like? North Korea could earn foreign currency and build anti-Washington alliances at the same time.
Under the new U.N. sanctions and the U.S.-led Proliferation Security Initiative, Washington, Tokyo, and Seoul are meant to intercept and interdict any such shipments from North Korea. However, Pyongyang states clearly that an attempted blockade of any kind by the United States and its allies would be regarded as an act of war and met with a decisive military response.
Given North Korea's capabilities and its threatening rhetoric, it's important to ask: How likely is it to act on brinkmanship threats?
The short answer: likely enough to worry. Although Washington might want to facilitate North Korea's implosion and collapse through long-term isolation, a desperate Pyongyang would almost certainly not go down quietly. Military conflict could lead to a full-scale war on the Korean Peninsula in which the possibility of nuclear weapons being used, as Pyongyang has ominously threatened, should not be ruled out. The regime would do anything to survive.
Over the long term, North Korea cannot tolerate isolation and economic sanctions. Economic development, which the country sorely needs, requires that Pyongyang open its doors to the international community, and especially to foreign investment, trade, and aid. But long before that happens, Pyongyang wants to address its foremost security concerns -- mainly from the U.S. threat (read: troops) just across the border in South Korea. Given Kim Jong Il's health problems and North Korea's ever worsening economic situation, Pyongyang is eager to push Washington into offering reliable security assurances and guarantees.
Regardless of Pyongyang's intention, Washington's only way to win this game is to prepare a large carrot to induce Pyongyang to denuclearize, while the United Nations and others, including China, prepare sticks to enforce the deal. Simply taking time and waiting would result in consequences in no one's best interests. Taking chances on an escalating game of chicken could ultimately leave both sides bloodied.