WASHINGTON - Japan's Takata Corp. rejected federal regulators' demand Wednesday for an expanded, nationwide recall of millions of air bags, setting up a possible legal showdown and leaving some drivers to wonder about the safety of their cars.

Amid the standoff, Honda Motor Co. decided to act on its own and recall cars with the potentially defective equipment in all 50 states. But other automakers have yet to make a decision.

At issue are air bags whose inflators can explode with too much force, hurling shrapnel into the passenger compartment. At least five deaths and dozens of injuries have been linked to the problem worldwide.

Over the last six years, Takata and 10 automakers issued a series of recalls covering eight million cars in the United States, mostly in high-humidity areas such as the Gulf Coast, because of evidence that moisture can cause the propellant to burn too quickly. But after incidents in California and North Carolina, the National Highway Traffic Safety Administration began pressing for the recall of eight million more vehicles from coast to coast - a demand that Takata rejected.

"There's not enough scientific evidence to change from a regional recall to a national recall," Hiroshi Shimizu, Takata senior vice president of global quality assurance, told a House subcommittee.

Takata also contends that NHTSA has authority to seek recalls only from auto manufacturers and makers of replacement parts, not from original parts suppliers - a position NHTSA contests.

Shimizu insisted that the air bags are safe: "I would drive a car with a Takata air bag."

David Friedman, NHTSA deputy administrator, said he was "deeply disappointed" by Takata's response.

The agency is now gathering proof that a recall is needed, which it will present at a public hearing. After that, NHTSA could order Takata to undertake a recall, and could take the company to court if it refuses.

Drivers whose cars have been recalled should have received notices in the mail. A driver can also key in the vehicle's identification number at www.safercar.gov or call the dealer.