A specialised US Air Force aircraft, known for its role in detecting nuclear explosions, was tracked conducting a flight across multiple American states on Thursday, raising eyebrows among observers monitoring global security.
The Flight Path of the 'Nuclear Sniffer'
Flight tracking data revealed the Boeing WC-135R Constant Phoenix aircraft taking off from its home at Offutt Air Force Base in Nebraska. The jet was then observed circling over South Dakota and making a loop near Fargo, North Dakota. At the time of reporting, the aircraft was continuing its mission above Rapid City, South Dakota.
The primary mission of the WC-135R is to collect atmospheric samples. Its sophisticated equipment is designed to detect and identify radioactive debris from nuclear explosions. This capability is crucial for verifying arms control treaties and bolstering national security by monitoring for illicit nuclear detonations and tracking fallout patterns.
Routine Training or Treaty Tensions?
The timing of the flight has drawn particular attention, as it coincides with the impending expiration of the New START Treaty between the US and Russia on February 5, 2025. This landmark agreement, signed on April 8, 2010, limits each side to 1,550 deployed nuclear warheads. Russian President Vladimir Putin proposed in September a 12-month extension to adhere to these limits, but US President Donald Trump has not yet formally responded.
However, US officials have not confirmed the specific reason for Thursday's mission. Experts note that domestic flights of the WC-135R are frequently conducted for crew training, equipment calibration, or routine background radiation monitoring. Such missions are not uncommon over the Midwestern United States, a region that hosts strategic nuclear assets. Many flights are simply 'baseline' collections to map normal global radiation levels rather than responses to specific incidents.
A Historic Programme of Airborne Detection
The Constant Phoenix programme has a long history, dating back to September 16, 1947, when General Dwight D. Eisenhower directed the Army Air Forces to develop a global atomic explosion detection capability. A historic early success came in September 1949, when a WB-29 collected debris confirming the Soviet Union's first atomic test—a development US intelligence had believed was years away.
The aircraft is a flying laboratory. It is equipped with:
- External flow-through devices that capture radioactive particulates on filter paper.
- A compressor system that collects whole-air samples in holding spheres for later laboratory analysis.
- An on-board suite that allows crews to detect radioactive "clouds" in real time.
The flight is operated by a cockpit crew from the 45th Reconnaissance Squadron at Offutt, while specialised equipment operators are assigned to Detachment 1 of the Air Force Technical Applications Center. The WC-135 fleet remains the US Air Force's sole platform for airborne nuclear air-sampling and continues to support the 1963 Limited Nuclear Test Ban Treaty.
Over the decades, these aircraft have conducted missions worldwide, from the Far East and Indian Ocean to the Mediterranean and polar regions. The predecessor WC-135W notably tracked fallout from the 1986 Chernobyl disaster. The most recent known deployment of the WC-135R was to the Middle East in 2024.
While the sighting quickly flooded social media with speculation linking it to the fragile state of nuclear diplomacy, the available evidence suggests a strong likelihood of a routine operational flight. The US Air Force typically does not publicly acknowledge such deployments unless they are directly tied to major international incidents.
