WASHINGTON (Reuters) - The U.S. government secretly shipped a large amount of deadly plutonium from a South Carolina site that produced the radioactive metal for nuclear bombs during the Cold War to Nevada, the Trump administration revealed on Wednesday.

The Justice Department, on behalf of the Department of Energy’s National Nuclear Security Administration, said in a notice filed with a U.S. court in Nevada that it could reveal the shipment of half a metric ton (1,100 pounds) because sufficient time had elapsed after the transfer to protect national security. The shipment occurred before November 2018.

The U.S. court in Nevada has been considering an effort by the state of Nevada to stop planned shipments of a metric ton of plutonium from South Carolina, that the Energy Department announced last August.

The plutonium was shipped from the K-Reactor at the Savannah River Site, the oldest reactor at the facility, to the Device Assembly Facility at the Nevada Nuclear Security Site, about 70 miles (112.65 km) north of Las Vegas.

The revelation angered politicians from Nevada, a sparsely populated state where the federal government has long wanted to store nuclear waste.

U.S. Senator Jack Rosen, a Democrat, said the NNSA misled a federal court “in a deceitful and unethical move, jeopardizing the health and safety of thousands of Nevadans and Americans who live in close proximity to shipment routes.”

She said she and other state politicians were prepared to take action against the NNSA.

Representative Dina Titus, another Nevada Democrat, said the shipments would bolster opposition to the storage of spent fuel from nuclear power plant in Nevada’s Yucca Mountain, a project on which billions of dollars has been spent that was closed by former President Barack Obama.

The NNSA said that due to security reasons no public notice was given ahead of the shipment and the highway route was not revealed. The department did not reveal when the shipment was made, other than it occurred before November 2018, before Nevada had sued to stop the proposed shipments.

The United States built the Savannah River Site during the 1950s to produce basic materials for nuclear weapons, mostly tritium and plutonium-239. In October the Trump administration killed plans to convert 34 tons of plutonium there into mixed oxide or MOX fuel for a specialized nuclear power reactor that has never been built in the United States.

Like the Obama administration before it, the Trump administration wants to dilute and bury that plutonium, potentially in New Mexico.