The government’s largest-ever claim for compensation relates to contamination with per- and polyfluoroaklyl substances, known as PFAS, at 28 bases. Human-made PFAS are commonly referred to as “forever chemicals” because they don’t break down naturally.

Australia filed the suit in the Federal Court of Australia against Minnesota-based 3M Company and its subsidiary 3M Australia.

3M said it would fight Australia’s claim.

“3M has never manufactured PFAS in Australia and ceased sales of the products at issue in Australia around two decades ago,” 3M said in a statement. “Despite this, the (Australian) Department of Defense continued to use PFAS-containing firefighting foams for nearly two decades longer.”

PFAS has been used since the 1950s in household and industrial products that resist heat, stains, grease and water. The firefighting foam containing PFAS was effective against fuel fires.

The Australian Defense Department warned residents near its Richmond Air Base outside Sydney in 2018 to reduce their consumption of locally produced fish and eggs, after PFAS was found in nearby groundwater.

Attorney-General Michelle Rowland on Thursday accused 3M of withholding information about environmental risks the foam posed.

“The Commonwealth (of Australia) is seeking more than AU$2 billion ($1.4 billion) in damages to recover significant past and future expenses incurred in investigating and managing contamination resulting from the historic storage and use of this foam,” Rowland told reporters.

Assistant Defense Minister Peter Khalil said his department had already spent AU$1.3 billion ($920 million) on managing and mitigating environmental impacts of the foam. The department had removed 200,000 metric tons (220,000 U.S. tons) of contaminated earth from bases and treated 13 billion liters (3.4 billion gallons) of contaminated water, Khalil said.

“We are prepared to take on powerful corporations when Australians and Australian communities have been impacted,” Khalil said.