In Detroit, there's a new sheriff in town — and he's cracking down on the U.S. auto industry.

When Mark Rosekind was sworn in as the new administrator of the National Highway Traffic Safety Administration (NHTSA) in December, the agency faced frequent ­criticism for its weak response to safety crises.

It was belittled on Capitol Hill during hearings over the General Motors ignition switch crisis last year and blamed for not taking aggressive action in 2009 when Toyota's sudden acceleration problems surfaced. And in 2013, the agency was openly challenged by Fiat Chrysler Automobiles on its initial call for recall of 2.6 million Jeep SUVs. The company then agreed to a lesser recall.

But last month, Rosekind's NHTSA unleashed a stunning display of force. After months of wrangling with Takata, one of the world's largest air bag manufacturers, Rosekind announced a consent agreement had been reached with the company to expand its recalls to nearly 34 million cars and trucks.

It's the largest consumer safety recall in U.S. history.

"I definitely think that NHTSA is getting tougher," said Michelle Krebs, senior analyst with AutoTrader.com. "They got clobbered with the Toyota recalls, and with the GM recalls for being too slow to do anything. Rosekind vowed in December that he is going to be tough and here it is."

Many automakers already have restructured how they monitor and report safety defects, but a tougher new regulatory era could force them to make even more changes, leading to more vehicle recalls and forcing automakers to spend more time and money self-policing their products.

Rosekind, 60, has a mandate to get tough on automakers over safety and compliance. He talked tough in his early days on the job, but few really knew what to expect until now.

Carrot and stick

He is wielding both a carrot and a stick.

Rosekind traveled to Detroit in April to meet top auto officials and see their safety technology. A week later, he dropped the hammer.

For the first time, Takata admitted that its air bag inflaters are defective in a recall that spans 11 different automakers, across multiple brands, makes and models.

The Takata news came just 24 hours after Rosekind said the agency would hold a public hearing on July 2 to force Fiat Chrysler Automobiles to explain what NHTSA says is a poor completion rate for repairing cars and trucks spanning 20 separate recalls affecting 10 million of the automaker's cars and trucks.

NHTSA also announced it would take charge of the Takata recall process, using legal authority it gained in 2000 but has never used before.

"He is going to be the cop on the beat. He doesn't care if he is popular or not," said safety advocate Joan Claybrook, a former NHTSA administrator. "I think he is going to get the agency back on track in terms of enforcing the law."

In 2014, there was a record number of vehicles recalled and massive publicity of the failings of the government, the agency and automakers including General Motors for its ignition switch recall, Honda and others tarnished by the Takata air bag recall and Jeep's battle over the safety of vehicles with gas tanks in the rear of the vehicles, to name a few.

Fallout from the high profile recalls reached a fever pitch last summer and continues today with ongoing criminal investigations, lawsuits, congressional hearings and recriminations, agency and third party investigations, and an overall public confusion and outcry that their safety was perhaps knowingly compromised.

'Newly acquired iron fist'

Into the fray walked Rosekind, a transportation safety professional and sleep expert, to succeed acting administrator David Friedman.

He pledged to make the roads safer again and observers say he is working to make good on it.

Those who have been NHTSA's harshest critics are beginning to praise Rosekind.

"The [Takata] story has played out as a win for the agency and another coat of polish on its newly acquired iron fist. And we find little to argue with there," Sean Kane, founder and president of Safety Research & Strategies said in a blog.

Still, concerns persist that NHTSA is understaffed and under funded.

With just 612 employees, the agency is responsible for overseeing the safety of all vehicles on the nation's roads and an auto industry that employs more than 900,000.

Using available tools

For now, Rosekind appears to be determined to use all of the tools the agency has, including some that it's never used before.

NHTSA recently said that it is extending its federal oversight of GM's handling of safety issues for an additional year, which means it will review all decisionmaking and communications.

The oversight authority comes from a consent order that GM agreed to in May 2014 following the recall of 2.6 million older model cars with potentially faulty ignition switches that had a defect the automaker knew about for years.

The agency also is for the first time exercising legal authority it gained in 2000 to coordinate Takata's air bag recalls.

All of this leaves automakers, such as Fiat Chrysler CEO Sergio Marchionne, uneasy.

"We are entering a new phase of regulatory oversight. I think we need to work with the agency to determine the proper level of cooperation," Marchionne said last week. "The real issue is that for organizations like ours, adjusting to this new regulatory environment is going to be painful."