With no breakthrough in sight regarding Takata Corp.'s faulty air bags and its handling of extensive recalls, U.S. transportation authorities are ratcheting up pressure on the embattled Japanese auto-parts supplier.

The world's No. 2 producer of air bags is widely seen as having been less than forthcoming in responding to the National Highway Traffic Safety Administration's probe into the root cause of the defective air bags and in taking responsibility for the problem.

Transportation Secretary Anthony Foxx has even characterized the company as a "bad actor." In February, he called on Congress to pass legislation to provide tools and resources "needed to change the culture of safety for bad actors like Takata."