NNSA manages three National Laboratories with rich histories supporting our national defense. The work at these laboratories and at NNSA's other sites  has enabled the United States to ensure the safety and effectiveness of the nation’s nuclear deterrent without underground nuclear testing for nearly 20 years. NNSA plays a key role in the nation’s efforts to keep nuclear materials out of the hands of terrorists. Our employees have helped improve security for nuclear materials in other countries and have worked with many nations to detect attempts to smuggle nuclear materials through ports and airports as well as across borders. The men and women who perform these jobs for NNSA are dedicated professionals who take pride in their work and comfort in the knowledge that they are performing a vital national service.