By George Friedman 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.