The Commerce Department is opening an investigation into whether imports of uranium — the chemical element that fuels nuclear power — pose a risk to national security.

The new probe marks the Trump administration’s latest use of a 1962 trade law to scrutinize imports. President Donald Trump has placed tariffs on foreign steel and aluminum following an earlier investigation, and the Commerce Department is conducting a review into auto imports.

Commerce is taking action after two American uranium producers, Energy Fuels and Ur-Energy, petitioned the department to open a so-called Section 232 investigation into whether the dominance of imports in the U.S. uranium market raises national security concerns.

“Our production of uranium necessary for military and electric power has dropped from 49% of our consumption to 5%,” Commerce Secretary Wilbur Ross said in a statement. “The Department of Commerce’s Bureau of Industry and Security will conduct a thorough, fair, and transparent review to determine whether uranium imports threaten to impair the national security.”

Tariffs on uranium would potentially raise prices for nuclear power plants at a time when many are struggling to turn a profit. The problem is particularly acute in the parts of the country with unregulated power markets, where they face tough competition from cheap natural gas and renewable energy.

Uranium also powers the Navy's nuclear submarines and aircraft carriers. However, the fleet runs on highly-enriched uranium, which the United States sources from its stockpile of weapons-grade material. The military will need new sources of fuel for naval purposes around 2060, according to a Department of Energy assessment.

Commerce said its investigation will examine the entire uranium sector, including mining, enrichment, defense and uses by industry. The department consulted with industry stakeholders, members of Congress and the departments of Defense and Energy prior to launching the probe.

Energy Fuels and Ur-Energy submitted their request to Commerce in January, arguing that imports of subsidized uranium from state-owned companies threatens to undermine national security.