As President Bush surveys the international landscape on the eve of his second term, he knows that his national-security team has its work cut out for itself.

Regrettably, the challenges won't end with capturing Osama bin Laden or this month's Iraqi elections. Foreign-policy powder kegs such as the Iranian nuclear program, the rise of China and the retrenchment of Russian democracy also loom large.

But of all the world's potential flashpoints, perhaps the most dangerous is the last vestige of the Cold War - the running standoff between communist North Korea and democratic South Korea.

So it's indeed propitious for us that retired army Green Beret and longtime Korea hand Gordon Cucullu has decided to pen "Separated at Birth," a highly readable book on this very subject.

In a breezy memoir/history suitable for the general reader, Cucullu sets out to help us understand the tremendous challenges involved in ending the war that never really ended. (Technically, the United Nations and North Korea are still at war - an armistice preserves the peace.)

Not satisfied by the 1950-53 Korean War stalemate, Kim Jong-Il's Stalinist North Korea still harbors an unrequited desire to reunite the divided peninsula under its communist flag. In hopes of reaching its increasingly unattainable goal, Pyongyang has developed the world's most repressive militarist police state. (No matter that people starve while North Korea spends 30 percent of its gross national product on the military.)

Brandishing chemical, biological and (possibly) nuclear weapons, North Korea's million-man army could unleash a torrent of death and destruction on South Korea's capital, Seoul, just 25 miles south of the misnamed Demilitarized Zone (DMZ), with little to no notice.

Still yearning for reconciliation, but unwilling to revisit the tragedies of the devastating Korean War, South Korea has fielded an armed force of 650,000, supported by an additional 30,000 U.S. troops under the command of a four-star American general. In contrast to its evil twin in the North, Seoul has developed into one of the world's most vibrant democracies and open economies.

But perhaps one of the most interesting elements of "Separated at Birth" is Cucullu's inference that managing relations with allies (i.e., South Korea) can be as challenging and complex as dealing with the vagaries of enemies (i.e., North Korea.)

Cucullu recounts well-known examples of North Korean perfidy, such as the 1976 axe murder of American servicemen at the DMZ over a tree-trimming, as well as the 1987 downing of a South Korean airliner by North Korean spies.

But he also tells of South Korea's lurching progress from authoritarianism toward democracy, including the 1979 Chun Doo-Hwan coup and the 1980 Kwangju massacre, to which some Koreans still believe (mistakenly) that American forces acquiesced.

Like the once-divided Germany, the two Koreas will inevitably be reunited. The question is when, how and under what conditions. "Separated at Birth" gives us insights into the historical, cultural, political and security challenges required in finding a permanent peace on an unsettled Korean peninsula.

Peter Brookes is a Heritage Foundation senior fellow.