Sen. John Barrasso, chairman of the Senate Environment and Public Works Committee, on Wednesday encouraged the Commerce Department to open an investigation into the national security impact of importing uranium from foreign countries.

American uranium producers Energy Fuels and Ur-Energy on Tuesday submitted a petition to the Commerce Department to investigate the national security effects of uranium imports from foreign state-owned firms in Russia, Kazakhstan, and Uzbekistan.

The petition was filed under Section 232 of the U.S. Trade Expansion Act of 1962, which allows the government to restrict imports for national security reasons, and Barrasso said he supports the aim of the two petitioners.

“For years, government-owned uranium producers in Russia, Kazakhstan, and Uzbekistan have unfairly flooded American markets with cheap uranium,” Barrasso, R-Wyo., said Wednesday, in a statement supporting the petition. “As a result, uranium production in the United States has fallen to the lowest levels we have seen since the early 1950s.”

“America’s ability to produce uranium is crucial to power our economy and keep our nation safe,” Barrasso continued. “It’s not only an energy security issue, it is a national security issue. The Trump administration needs to expedite this investigation and take action to preserve this vital industry.”

Imports of uranium, the fuel for nuclear power, from state-subsidized companies in Russia, Kazakhstan, and Uzbekistan provide nearly 40 percent of U.S. uranium, the Environment and Public Works Committee said.

The U.S. produces less than five percent of its uranium. More than half of U.S.-based uranium production occurs in Wyoming, Barrasso’s home state.

America’s 99 nuclear power plant reactors are dependent on foreign sources for about 90 percent of their fuel needs, the committee said.

The U.S. nuclear industry is facing numerous challenges.

All plans to build new nuclear plants in the U.S. have been canceled, except for one in Georgia.

Today, 60 percent of the carbon-free energy produced in the U.S. comes from the nation's existing 99 nuclear power plants. Nearly 20 percent of the nation’s electricity is provided by nuclear energy.

But the Energy Information Administration projects the share of nuclear in the country’s electricity grid to fall by nearly half through 2050, to 11 percent. The industry hopes investments in small, modular reactors can reduce costs and address safety and proliferation concerns.