Steve Andreasen is a national security consultant to the Nuclear Threat Initiative and its Nuclear Security Project in Washington, DC, and teaches courses on National Security Policy and Crisis Management in Foreign Affairs at the Humphrey School of Public Affairs.

He served as director for defense policy and arms control on the U.S. National Security Council at the White House from February 1993 to January 2001. He was the principal advisor on strategic policy, nuclear arms control, and missile defense to the National Security Advisor and the President. During the Bush Sr. and Reagan administrations, Andreasen served in the U.S. State Department's Bureau of Politico-Military Affairs and the Bureau of Intelligence and Research, dealing with a wide range of defense policy, arms control, nuclear weapons, and intelligence issues.

As a presidential management fellow, he served as a special assistant to Ambassador Paul H. Nitze in the U.S. State Department, focusing on the Strategic Arms Reduction Talks, and as a foreign policy and defense legislative assistant in the office of U.S. Sen. Albert Gore Jr. Andreasen received his BA from Gustavus Adolphus College in 1984 and earned his MA from the Humphrey School in 1986.

In 2002, Andreasen was the Democratic candidate for Congress in Minnesota's 1st Congressional District.

His articles and opinion pieces have been published in Foreign Affairs, Survival, The Washington Post, Los Angeles Times, Minneapolis Star Tribune, St. Paul Pioneer Press, Boston Globe, San Jose Mercury News, San Francisco Chronicle, Philadelphia Inquirer, Baltimore Sun, Politico, Arms Control Today, Strategic Survey, In the National Interest and the Guardian.