Story highlights Haley urged Secretary Ernest Moniz to "stop shipment or re-route"

Haley said the shipments put her state "at risk for becoming a permanent dumping ground"

(CNN) South Carolina Gov. Nikki Haley is demanding the Department of Energy stop a planned shipment of nuclear material from reaching her state's shores.

Haley urged Secretary Ernest Moniz in a letter Wednesday to "stop shipment or re-route" about 730 pounds of weapons-grade plutonium from Japan destined for a nuclear storage and processing site in her state, according to a copy of the letter Haley's office provided to CNN.

"Continued shipments of plutonium into our state puts South Carolina at risk for becoming a permanent dumping ground for nuclear materials. It is imperative to the safety of our citizens and our environment that South Carolina not allow this to happen," Haley wrote.

The U.S. government and Japan agreed to the shipment during the March 2014 Nuclear Security Summit as part of an international effort to improve global nuclear security and reduce nuclear stockpiles around the world. The U.S. is slated to convert the weapons-grade plutonium "into less sensitive forms," the White House said in a statement at the time.

Haley's demands could now throw a wrench in those efforts before the next Nuclear Security Summit, set to take place in Washington at the end of the month.

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