Nineteen years ago, I was in Ukraine when the last nuclear warheads, orphaned during the Soviet Union’s breakup, rolled out of the country. As an assistant secretary of Defense at the time, I had worked with Washington colleagues and foreign counterparts to eliminate those nuclear weapons and thus one danger at the dawn of the post-Cold War world. Together — with bipartisan support in Congress led by Sens. Sam Nunn, a Democrat, and Richard Lugar, a Republican — we succeeded.

Today, the Iran deal provides the opportunity to address an even greater nuclear threat. Congress should support it because, once implemented, the deal will remove a critical source of risk and uncertainty in a vitally important but tumultuous region.

Dr. Ashton B. Carter and Ambassador Robert G. Joseph discuss recommendations stemming from recommendations in final report of the review they co-chaired of the Defense Threat Reduction Agency (DTRA) and other DOD efforts to counter weapons of mass destruction.

Should the United States allow a country openly hostile to it and armed with nuclear weapons to perfect an intercontinental ballistic missile capable of delivering nuclear weapons to U.S. soil? We believe not. If North Korea persists in its launch preparations, the United States should immediately make clear its intention to strike and destroy the North Korean Taepodong missile before it can be launched.

The fallacy in the Bush administration's appointment of a commission to study intelligence failures is that there is almost never such a thing as a pure intelligence failure. Intelligence failure is usually linked to policy failure.

Ashton B. Carter, Arnold Kanter, and William J. Perry write about the viability of the Nonproliferation Treaty in this New York Times op-ed.

Ashton B. Carter, William J. Perry, and John M. Shalikashvili address the danger of loose nukes in North Korea in this Wall Street Journal op-ed.

Ashton B. Carter and William J. Perry remember the 1994 North Korean nuclear crisis in this New York Times op-ed.

Carter & Perry call for determination and patience in responding to the North Koreans' recent revelation of their nuclear program.

Dr. Ashton B. Carter's op-ed in the Washington Post.