CHEMICAL, BIOLOGICAL, RADIOLOGICAL, AND NUCLEAR OPERATIONS FM 3-11 April 2025 As the United States Army operates in potential chemical, biological, radiological, or nuclear (CBRN) environments in the 21st century, we must account for new and emerging CBRN threats. Many peer, near-peer, and even sub-peer adversaries make operating in a CBRN environment inherent to conducting operations. Compounding this challenge is 20 years of CBRN skills atrophy created by support to counterinsurgency operations that lacked large-scale CBRN threat. Additionally, the Army's approach to countering CBRN threats and hazards capabilities is outdated - avoid by detecting hazards using equipment that cannot detect all hazards and which require personnel to manually place into operation, protect with burdensome and cumbersome equipment which reduces combat effectiveness, and decontaminate employing old resource intensive equipment. The proliferation of weapons of mass destruction (WMD) and the inability of the international community to deter, attribute, and impose costs for their use indicate that CBRN threats will likely continue to increase. In the past ten years, the Syrian, Russian and North Korean governments have approved and employed WMD. The Syrian government used WMD on its own population while Russia and North Korea employed WMD for small scale assassinations in England and Malaysia respectively. In contravention of international treaties, these and other state actors continue to maintain formidable stockpiles and the ability to rapidly increase production of CBRN capabilities. Ever improving technologies make it easier to develop and manufacture WMD or transition dual-use facilities which do not violate treaty requirements. Also, nonstate actors continue to pursue proliferation agendas, making WMD a global challenge. Recent experimentation focused on 2040 depicts a more transparent future battlefield for both friendly and enemy forces—if you can be seen you can be hit. We can also expect a hyperactive tactical area making situational understanding critical for commanders and leaders at every echelon. The ability to make proactive risk-based decisions before entering a potential hazard area will prove critically important to ensure both Soldier survivability and mission success.