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:
The trustees of Columbia University refused to accept Eisenhower's resignation in December 1950, when he took an extended leave from the university to become the Supreme Commander of the North Atlantic Treaty Organization (NATO), and he was given operational command of NATO forces in Europe. Eisenhower retired from active service as an Army general on May 31, 1952, and he resumed his presidency of Columbia. He held this position until January 20, 1953, when he became the President of the United States.

Question:
What job did Eisenhower hold after his second tenure as president of Columbia?

President of the United States