U.S., Australia Conduct Joint Chemical, Biological Exercise

Published Aug. 29, 2025
By Marine Capt. Isis Coty and Cpl. Annabelle Reed-O'Brien, 1st Marine Aircraft Wing

Marines assigned to Marine Wing Support Squadron 174, Marine Aircraft Group 24, 1st Marine Aircraft Wing, joined forces with the Air Force, Air Force Reserves, Air National Guard and Royal Australian Air Force for Exercise Toxic Swell 25. The two-week training event on the island of Oahu, Hawaii, focused on enhancing chemical, biological, radiological and nuclear defense capabilities in a joint environment.

A person wearing a camouflage personal protection equipment wipes a substance on the floor of an aircraft.

A close-up picture of the hand of a person wearing a camouflage personal protective equipment, wiping a substance on the floor of an aircraft. Smoke is rising from a rusted metal handle.

Toxic Swell 25 went beyond the conventional classroom settings for CBRN exercises, with 10 units collaborating to train in an austere environment. Participants engaged in multiple field rehearsals, including runway survey missions, simulated infantry drills, aircraft decontamination and CBRN detection scenarios. Marines, airmen, National Guardsmen and RAAF partners conducted military operations on urbanized terrain, simulating the challenging conditions personnel might face in actual deployments. The exercise emphasized joint movement to objectives and effective use of CBRN training across services and with partnered nations.

"Exercises like Toxic Swell test our response to worst-case scenario CBRN threats that our enemies may use," said Marine Corps Chief Warrant Officer 2 Joshua Webb, who served as officer in charge of the exercise. "The training we conducted blended basic Marine [Corps] warfighting tactics with the knowledge of the Air Force and RAAF, teaching each other how we can best move as a team to the objective and use our CBRN training effectively."

A person wearing a camouflage military uniform sprays a substance from a hose onto another person wearing camouflage personal protective equipment while a group of people stand and watch.

A key highlight of Toxic Swell was the participation of RAAF, which brought extensive expertise in CBRN threats to the exercise. The RAAF conducted an in-depth session to educate participants on their mission oriented protective posture gear removal process. The demonstration provided valuable insight into how U.S. partner nations combat CBRN situations, enhancing the knowledge of U.S. service members who may operate together in future joint missions.

"Having been part of Toxic Swell 24, we came to observe and provide training feedback to our units," said Flight Sgt. Noel Klaehn, assigned to the 295th Squadron, RAAF Combat Support Group. "Most of our operations are likely to be with allied forces, so exercises like this are critical. We hope to bring more of our team to participate next year."

In addition to the RAAF training, participants completed the performance evaluation checklist for weapons handling and proficiency on the M16A4 rifle and M240B machine gun, as well as the gas chamber, where they practiced donning and clearing their protective masks in a controlled environment. This experience reinforced the importance of proper CBRN procedures and ensured the participants received standardized Marine Corps training, enabling a diverse team to merge seamlessly.

A person wearing camouflage personal protective equipment scans the door of an aircraft in a woodland environment.

By the conclusion of Toxic Swell 25, all training objectives were successfully executed, fusing CBRN response with traditional infantry tactics and command coordination. Through realistic training, the participants became a cohesive, capable force ready to respond to any CBRN threat.