Ever since the end of the Korean War in 1953, North and South Korea have uneasily coexisted on either side of a tense and heavily fortified "demilitarized zone" (DMZ). In the North, a secretive totalitarian Communist regime has ruled over a starving, tightly controlled population. In the South, a vibrant democracy, protected by U.S. troops, has produced one of the world's most technologically advanced economies.
Not at war, but not at peace either, the two nations have maintained a mostly nonviolent standoff, with hopes on both sides for an eventual reunification of the two Koreas.
But recent actions by North Korea and its young, unpredictable leader, Rim Jong Un, have raised the threat of a military confrontation. Last month, the North declared the armistice that ended the war and has largely kept the peace for the last 60 years "nullified." And it threatened to launch a "pre-emptive nuclear strike" against South Korea and the United States. In response, the U.S. sent B-2 stealth bombers over South Korea in a show of force.
It's difficult for outsiders to know exactly what Kim's true intentions are, but given North Korea's history of provocative actions and bizarre behavior, the threats are being taken seriously. Taking no chances, the U.S. announced it would spend $1 billion on additional missile defenses in Alaska and California.
"The Korean peninsula is heading into a difficult and very dangerous period," says Donald Gregg, a former U.S. ambassador to South Korea.
Tensions on the Korean peninsula are nothing new. When World War II ended in 1945, the Soviet Union occupied the north and installed a Communist regime, while U.S. and Allied forces controlled what became South Korea.
In 1950, North Korea invaded the South. The United Nations called up an international force to defend South Korea, with the U.S. supplying 90 percent of the troops. By the time the fighting stopped in 1953, 34,000 Americans had been killed. North and South Korea signed an armistice but never a peace treaty.
When the Soviet Union collapsed in 1991, North Korea's economy began a catastrophic decline. While millions starved, the regime spent a fortune to maintain what is now a million-man army and build up a secret nuclear-weapons program.
In 2006, North Korea announced it had exploded a nuclear bomb. Three years later, it tested missiles and expelled U.N. nuclear inspectors. In 2010, North Korea revealed a uranium-enrichment plant at Yongbyon thought to be for producing more nuclear weapons. In February, it conducted a third nuclear test against the wishes of its only major ally, China.
All this is deeply troubling to the U.S.--which has 28,000 troops in South Korea, within easy range of a North Korean attack.
The threats are influencing South Korean public opinion as well: Polls indicate that two thirds...