Defense Secretary Robert Gates has announced plans to retire by the end of next year.

Gates said leaving the Pentagon in 2011 makes sense because it gives him time to oversee the major offensive in Afghanistan and bow out before the presidential elections in 2012.

Gates was appointed Defense Secretary by President Bush in 2006. He stayed on at the request of President Obama.

The White House said Gates has served the country with distinction. There is no word yet on who might succeed him.