The U.S. federal agency in charge of vehicle safety said Tuesday that any decision to open formal investigations is an “independent process” and that it asked for cooperation from Tesla Motors Inc. (NASDAQ:TSLA) regarding a “preliminary evaluation” into whether the Model S electric sedan’s battery casing is sufficient to avert so-called thermal runaway fires.

The response comes after Tesla CEO Elon Musk said the following in an overnight blog post ahead of the NHTSA’s formal announcement on Tuesday morning.

“We have requested that the National Highway Traffic Safety Administration conduct a full investigation as soon as possible into the fire incidents,” Musk said in a 1,400-word rebuke of insinuations that the Model S poses a greater fire risk than vehicles that run on gasoline. Musk says his vehicle is getting unwarranted attention from the sensationalistic “popular and financial media.”

For its part the NHTSA clarified media requests, including from the popular New York Times, to clarify Musk’s claim he invited the agency to investigate the Model S to put to bed these insinuations.

Here’s the statement from the National Highway Traffic Safety Administration:

 “NHTSA’s decision to open any formal investigation is an independent process. In regards to Tesla, the agency notified the automaker of its plans to open a formal investigation and requested their cooperation, which is standard agency practice for all investigations.  The automaker agreed to do so.”