This week, Energy Department Secretary Rick Perry sent a letter to Nevada Senator Catherine Cortez Masto saying that the Department would move a half-ton load of plutonium waste out of Nevada between 2021 and 2026.

Last year, the federal government said it would move plutonium from South Carolina to the Nevada National Security Site (NNSS) for temporary storage before moving it on to its final destination. The state of Nevada sued the federal government in the hopes of stopping the planned shipment, but months into the legal action, the federal government told the court that the plutonium had already been secretly delivered to the NNSS.

Nevada politicians were incensed, and Cortez Masto, who holds a seat on the Senate Committee on Energy and Natural Resources, placed holds on any pending Trump administration nominations to the Department of Energy.

The Associated Press reports that Cortez Masto said she would drop the holds she placed on nomination proceedings for DOE employees after receiving the letter from Perry promising to move the shipped plutonium out of her state. Perry's letter also promised that no future shipments from South Carolina would be made to Nevada.

The shipment of plutonium occurred as part of a separate 2017 order from the South Carolina US District Court, which required that the DOE remove one ton of defense plutonium from the site of the failed Mixed Oxides Fuel Fabrication Facility (MFFF). The MFFF would have reprocessed weapons-grade plutonium for use in commercial nuclear reactors, but as costs mounted, the Trump administration cancelled the project. (Earlier this year, the Department of Justice filed a complaint against MFFF contractors and subcontractors, alleging that they billed the US government for supplies that were never delivered.)

As part of the agreement between Cortez Masto and Perry, the two will take a tour of the Device Assembly Facility at the NNSS where the plutonium that is already in Nevada will be housed for two years, according to the Las Vegas Review Journal. Perry also "announced about $1 billion in upgrades at the Nevada security site where the weapons-grade plutonium is being stored."

Still, the Nevada Attorney General's office "is seeking a formal court order preventing any shipments because it says the agency’s track record shows it cannot be trusted," the Associated Press wrote.

Nevada politicians are largely opposed to another nuclear waste storage project planned for Nevada, at Yucca Mountain, which the Trump administration has said it wants to revive. However, the revival of the Yucca Mountain project has stalled, and if the facility were to be completed, it would be used for commercial nuclear waste rather than defense-related nuclear waste. The ultimate destination for the plutonium from South Carolina is expected to be the existing Waste Isolation Pilot Plant (WIPP) in New Mexico.