After U.S. President Barack Obama visited the Korean Demilitarized Zone on March 25 during his trip to South Korea for a nuclear security summit, he made the obligatory presidential remarks warning North Korea against continued provocations. He also praised the strength of U.S.-South Korean relations and commended the 28,500 U.S. troops stationed there. Obama's visit itself is of little importance, but it is an opportunity to ask just what Washington's strategy is in Korea and how the countries around North Korea (China, Russia, South Korea and Japan) view the region. As always, any understanding of current strategy requires a consideration of the history of that strategy.
The Korean War and the U.S. Proto-Strategy
Korea became a key part of U.S. Cold War-era containment strategy almost by accident. Washington, having deployed forces in China during World War II and thus aware of the demographic and geographic problems of operating on the Asian mainland, envisioned a maritime strategy based on the island chains running from the Aleutians to Java. The Americans would use the islands and the 7th Fleet to contain both the Soviets and the Chinese on the mainland.
Korea conceptually lay outside this framework. The peninsula was not regarded by the United States as central to its strategy even after the victory of the communists in the Chinese civil war. After World War II, the Korean Peninsula, which had been occupied by the Japanese since the early 1900s, was divided into two zones. The North came under the control of communists, the South under the control of a pro-American regime. Soviet troops withdrew from the North in 1948 and U.S. troops pulled out of the South the following year, despite some calls to keep them in place to dissuade communist aggression. The actual U.S. policy toward an invasion of the South by the North is still being debated, but a U.S. intervention on the Korean Peninsula clearly violated Washington's core strategic principle of avoiding mainland operations and maintaining a strategic naval blockade.