Analysis
Brennan’s claim accurately reflects that **climate change is formally designated a national security threat** by the U.S. Department of Defense (DoD), Director of National Intelligence, and NATO, with bipartisan acknowledgment in documents like the 2022 National Security Strategy. However, the 'debate' she references is largely confined to **partisan political discourse** (e.g., some congressional Republicans downplaying linkages) rather than operational military or intelligence assessments. Her statement conflates **public politicization** with the **institutional consensus**, which is robust but not universal in implementation (e.g., budgetary priorities).
Background
The DoD has labeled climate change a 'threat multiplier' since at least 2010, citing risks like resource scarcity, migration pressures, and infrastructure vulnerabilities. While the Biden administration elevated climate security as a priority, earlier Trump-era policies (e.g., 2017 NSS omission) highlighted partisan divides. Globally, militaries (e.g., UK MoD, EU) treat climate as a destabilizing factor, though domestic U.S. framing remains polarized.
Verdict summary
While climate change is widely recognized as a security threat by experts and U.S. agencies, Brennan’s framing oversimplifies the *extent* of active debate, which persists more in political rhetoric than among policymakers or military leaders.