An open records lawsuit filed against the State Department is attempting to uncover whether Russian entities attempted to financially support U.S. environmentalist causes.

The Institute for Energy Research (IER) — a free-market energy group based in Washington, D.C. — filed the lawsuit on Monday. IER has requested the State Department to hand over correspondence concerning hydraulic fracturing, environmental advocacy and Russia that was exchanged to and from high-ranking employees.

The lawsuit follows a Freedom of Information Act request filed by IER back in October. However, the free-market group claims State Department officials are dragging their feet on providing the requested information.

“Any foreign attempts to covertly influence U.S. energy policy must be exposed and met with full consequences,” read a Monday statement from IER President Thomas Pyle. “Particularly given what we have already learned, the State Department’s evident lack of interest in examining this issue of obvious concern to congressional oversight, or in bothering with a substantive response to our request even when pressed, is deeply concerning.”

The State Department failed to hand over responsive records to IER by Nov. 23, despite a legal obligation to do so, according to the free-market group’s press release. Department officials have cited a “backlog” as reason for their slow pace, and have only acknowledged receipt of the request.

“We hope State corrects this matter immediately by providing the necessary records to document what has been happening behind the backs of the American people. The State Department must be clear: foreign meddling in U.S. energy policy or markets will not be tolerated under any circumstances,” Pyle continued in his statement.

The lawsuit follows mounting questions over Russian support of environmentalist groups that have opposed U.S. fracking. American officials confirmed back in 2017 that RT, a Kremlin-controlled media outlet, ran anti-fracking programming with an intent to protect Russian energy interests. Former Secretary of State Hillary Clinton told an audience behind closed doors that Russia’s government was propping up “phony environmental groups” opposed to hydraulic fracturing and pipelines, according to emails released by Wikileaks in 2016.

IER’s lawsuit also seeks to obtain correspondence from Texas Republican Rep. Lamar Smith who, as chair of the House Science Committee, has also made inquiries into the matter.

The U.S. shale oil boom has given Russia reason to worry. Moscow’s has long been able to wield its influence over European politics with the help of its vast natural gas supply. However, with more European nations turning to the U.S. for its natural gas needs, Russia has been slowly rendered less dominant.

Thanks in large part to the implementation of hydraulic fracturing, the U.S. has reached record levels of natural gas production.