You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Dwight_D._Eisenhower

Context:
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.

Question:
What American official notably opposed the armistice?

Secretary Dulles