Attorney General Aaron Ford launched a legal effort Thursday to prevent the Department of Energy from making further shipments of plutonium to the state.

The filing comes as an appeal is pending to reverse a Reno judge’s ruling denying a similar request the state made last week.

“Today’s motion represents another step in our aggressive, multifaceted legal strategy to prevent Nevada from becoming a parking lot for nuclear weapons and waste,” Ford said in a release.

The state’s motion was filed in U.S. District Court in Nevada and requests an injunction barring DOE from shipping plutonium to the state while the state appeals the Reno judge’s ruling.

The state’s action followed the disclosure by DOE last week that it secretly shipped a half ton of weapons-grade plutonium before last November to the Nevada National Security Site, about 65 miles northwest of Las Vegas, while the state was negotiating with the agency to prevent any such shipments.

Nevada sued the DOE in November after negotiations did not produce a resolution. The DOE’s disclosure was made in a court filing related to the suit. A day after the DOE’s admission, a Reno judge denied the state’s request that DOE be barred from shipping more plutonium to Nevada.

“When the Department of Energy takes unilateral action to ship dangerous material to Nevada, it robs the State of our ability to prepare for the risks associated with transporting and storing plutonium,” Ford continued. “Frankly, the Department of Energy has lost all credibility and trust, and its assurances that it will not ship any plutonium in the future aren’t worth the paper they’re written on.”

Nevada’s appeal to the Ninth Circuit comes after Gov. Steve Sisolak sent a terse letter to Energy Secretary Rick Perry Wednesday asking a series of questions, including what is the current overall capacity for the Device Assembly Facility (DAF), has the DAF been used previously to store or stage weapons-grade for defense purposes, and whether plutonium shipped to Texas will be shipped to Nevada. He said he wants a response to his questions by Feb. 19.

The DAF is a collection of more than 30 individual steel-reinforced concrete buildings connected by a rectangular common corridor. The entire complex, covered by compacted earth, spans an area of 100,000 square feet. It was a key part of the national nuclear weapons testing program, which has been frozen under a moratorium that began in October 1992.

“While you have shown little regard for maxims of states rights, it is nonetheless a bedrock concept of this country and a principle I demand that you respect,” Sisolak wrote. “To that end, and to allow me to faithfully discharge my obligations to protect my State and its people, I ask that you provide full and complete answers to the following questions.”

Correction 4:14 p.m.: This story was updated to reflect that the state filed its motion in U.S. District Court in Nevada.