Abstract: With geopolitical and technological changes mostly driven by the nuclear weapons states, we are slipping towards a new arms race and deterioration of the multi-decade arms control regime. This talk will describe the current critical situation, feasible steps to reduce the nuclear threat, and a new project sponsored by the American Physical Society to engage physical scientists in advocacy for nuclear threat reduction. After the colloquium a short meeting will be held for those interested in learning about the APS Physicists Coalition for Nuclear Threat Reduction.