The Department of Justice (DOJ) said it would prosecute anyone responsible for damaging the nation’s oil and natural gas pipelines, three weeks after 84 House lawmakers posed a series of questions in a letter to Attorney General Jeff Sessions over destruction by demonstrators.

On Monday, a DOJ spokesman told NGI that the department appreciates “the members’ letter,” and is reviewing it.

“This is a critically important issue,” he said. “Oil and natural gas pipelines provide vital services to millions of Americans. Attempts to damage or shut down these pipelines not only deprive local communities of these services, they can put American lives at risk, cost taxpayers millions of dollars, and threaten our environment.”

The DOJ added that it is “committed to vigorously prosecuting those who damage this critical energy infrastructure in violation of federal law.”

In the Oct. 23 letter, Rep. Ken Buck (R-CO) and his colleagues cited media reports of protesters attempting to disrupt oil and gas transmission through interstate and international pipelines, including some instances of protesters using “blow torches to burn holes in pipelines or promoted violence against oil and gas company employees.”

The House lawmakers asked the DOJ if existing federal statutes, including the Patriot Act and the Pipeline Safety Act, are adequate tools for investigators to levy federal charges against protesters who damage pipelines. They also asked whether the DOJ had decided to prosecute or investigate a series of incidents on Oct. 11, when protesters damaged four major crude oil pipelines in multiple states, or if attacks against the nation’s energy infrastructure could be classified as domestic terrorism.

Last month, the American Petroleum Institute (API) said it supported the lawmakers’ letter and disclosed that it was working with the Trump administration on the issue. API said other federal agencies, including the Federal Bureau of Investigation and the Transportation Department’s Pipeline and Hazardous Materials Safety Administration, were also involved.