DETROIT (AP) — A dispute between U.S. safety regulators and air bag maker Takata Corp. escalated Wednesday when the government threatened fines and legal action if the company fails to admit that driver's side air bag inflators are defective and agrees to a nationwide recall.

In a letter to Takata's Washington office, the National Highway Traffic Safety Administration gave the Japanese company until Tuesday to file paperwork declaring a defect and agree to expand the recall from high-humidity states to the full nation.

The company's air bags have been blamed for at least five deaths and multiple injuries worldwide. They can inflate with too much force, blowing apart a mental canister and sending shrapnel into drivers and passengers.

The letter is the first step in a legal process to compel a recall. To do so, the agency must make a finding that there's a safety defect, hold a public hearing and then it can go to court. It can also fine the company up to $7,000 per vehicle with defective inflators, and NHTSA says there are millions on the road today.

"Be assured that we will use all of our authority and resources to ensure that America's drivers and passengers are safe." Transportation Secretary Anthony Foxx said in a statement.

Takata has maintained that the air bag problems are caused by prolonged exposure to airborne moisture, and that there's no need for a national recall. Boundaries of the recall zone vary by manufacturer, but generally it covers Gulf Coast states, Hawaii, Puerto Rico and some U.S. territories.

A company spokesman said Wednesday that he was working on a response to the government letter.

In the letter, NHTSA says Takata hasn't filed a safety defect letter as demanded by the agency on Nov. 18. The company, the letter said, has not provided an explanation for two driver's side air bag inflator ruptures outside the high-humidity areas.

"Despite the severe consequences of air bag ruptures and mounting data demonstrating a safety defect, Takata responded that it did not agree with NHTSA's basis for a nationwide recall," the letter stated.

The agency cites a May 31 inflator rupture in California that injured the driver of a 2005 Honda Accord and an Aug. 17 case in North Carolina in which the driver of a 2007 Ford Mustang was hurt.

About 8 million vehicles from 10 manufacturers have been recalled in the U.S., and nearly 14 million worldwide. The vehicles have Takata driver's side or passenger side air bags, or both. So far the government is not seeking a national recall of passenger side air bags.

Lawmakers have said there are 100 million cars and trucks in use worldwide with Takata air bags, and more than 30 million in the U.S.

Recently NHTSA has gotten tough with Takata on the air bag issue, but lawmakers have criticized the agency for a slow and haphazard response to a problem that has been unfolding since at least 2008.