When I began my career in elementary particle physics, the great figures who taught and inspired me had been part of the Manhattan Project generation that developed the atomic bomb. They were proud to have created a “disruptive” technology that ended World War II and deterred a third world war through more than 50 years of tense East-West standoff. They were also proud to have made nuclear power possible. But their understanding of the underlying technology also gave them a deep regard for the awesome, unavoidable risks that came with those technologies.

Ash Carter discusses public service, opening the military to transgender troops, and North Korea's latest missile launch with actor Jim Parsons on his SiriusXM radio show "Jim Parsons Is Too Stupid For Politics."

For the seventh year in a row, Congress has failed to pass a defense appropriations bill in time to start the fiscal year. And for the past four years, the Defense Department and other federal agencies have been struggling with the impact of sequestration, which imposed cuts that were never meant to be implemented, but were supposed to prod both parties to come together and reach a budget agreement. The Defense Department has done its best to manage through this prolonged period of budget uncertainty, making painful choices and trade-offs among the size, capabilities and readiness of the joint force.

The nation cannot allow this to become the new normal.

PDP Co-Director Dr. Ashton B. Carter explores the daunting list of national security challenges facing the next American president.

This report of the International Security Advisory Board (ISAB) offers nineteen recommendations for discouraging a cascade of nuclear weapons states.

Failure to develop a comprehensive contingency plan, such as the one proposed here, and inform the American public, where appropriate, about its particulars will only serve to amplify the devastating impact of any nuclear attack on a U.S. city

Former Clinton administration officials Ashton Carter and William Perry argue that the most effective way to curb the threat from Pyongyang is to destroy its missiles at their test sites

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.

Dr. Ashton B. Carter testifies before the Senate Committee on Foreign Relations.

Dr. Ashton B. Carter testifies before the Senate Foreign Relations Committee.