(Bloomberg) -- The Takata Corp. air-bag recall already affectinga dozen automakers in the U.S. may widen as the nation’s regulatorheightens its scrutiny of the devices.

Volkswagen AG, Daimler AG, Jaguar Land Rover and Tesla MotorsInc. are among carmakers still using Takata air bags with ammoniumnitrate, a chemical propellant that U.S. safety regulators are nolonger confident in. Transportation Secretary Anthony Foxx saidthose automakers could also be affected by recalls that alreadyinvolve about 19 million vehicles.

“Everyone’s got to be vigilant,” Foxx said in an interviewMonday at a U.S.-Japan Council conference in Tokyo. “Even thoughour focus has been on the 12 manufacturers that we know pose a riskto safety of our consumers, it doesn’t preclude companies fromdoing their own testing. Our investigation remains open, so Iwouldn’t preclude the possibility that other OEMs would beaffected.”