In July 1953, an armistice took effect with Korea divided along approximately the same boundary as in 1950. The armistice and boundary remain in effect today, with American soldiers stationed there to guarantee it. The armistice, concluded despite opposition from Secretary Dulles, South Korean President Syngman Rhee, and also within Eisenhower's party, has been described by biographer Ambrose as the greatest achievement of the administration. Eisenhower had the insight to realize that unlimited war in the nuclear age was unthinkable, and limited war unwinnable.