Two key House Republicans asked Treasury Secretary Steven Mnuchin to investigate allegations that Russia interfered in U.S. energy markets by making millions in contributions to environmental groups opposed to hydraulic fracturing (fracking) in order to sow domestic discord.

In a six-page letter to Mnuchin dated June 29, U.S. Reps. Lamar Smith (R-TX) and Randy Weber (R-TX) accuse Russia, through government-run corporations like Gazprom, of waging a “propaganda war against fossil fuels” by channeling funds to anti-fracking groups in the U.S. through Bermuda.

“It is easy to see the benefit to Russia and Gazprom that would result from a reduction in the U.S. level of drilling and fracking — a position advocated for by numerous environmental groups in the U.S.,” Smith and Weber wrote. They added that publically available documents point to a “complex scheme operated under the guise of philanthropic endeavors.

“The Russian government and complicit parties have executed a political agenda with little or no paper trail. This scheme allows money originating from foreign countries like Russia to funnel through Bermuda-based shell companies to environmental groups in the United States with the aim of disrupting the U.S. energy industry. These allegations are ripe for investigation by the Department of Treasury.”

According to Smith and Weber, the documents show entities connected to the Kremlin used Klein Ltd., a shell company registered in Bermuda, to send tens of millions of dollars to the Sea Change Foundation, a 501(c)(3) organization based in the United States. Sea Change then allegedly passed the money along to environmental groups, including the Sierra Club, the League of Conservation Voters and the Natural Resources Defense Council.

The lawmakers added that tax records show Klein contributed $23 million to Sea Change in 2010 and 2011. The contributions from Klein accounted for nearly half of total contributions to Sea Change during that time frame.

“Klein’s contributions to Sea Change are not by chance,” Smith and Weber said. “Sea Change’s founder and president, Nat Simons, is appropriately positioned to give the Russian funds to environmental groups that push back on U.S. domestic fracking and gas advancements. Nat Simons has said the mission of Sea Change is to facilitate the transfer of money and advance a shift away from carbon-based energy.”

In related matters, a group of Democratic senators last month urged President Trump to direct the Department of Energy to examine the threats Russian hackers pose to energy infrastructure in the United States. Lawmakers from both parties have also bristled at Trump’s suggestion that the U.S. create a cybersecurity unit with Russia, an idea formed on the sidelines of last week’s G20 summit in Hamburg, Germany.