Dozens of members of Congress want U.S. Attorney General Jeff Sessions to consider domestic terrorism charges for protesters who oppose pipeline construction projects, like those who rallied against the Dakota Access pipeline in Iowa.

In a letter to Sessions this week, 84 members of Congress said that "maintaining safe and reliable energy infrastructure is a matter of national security." They alluded to the national protests sparked by the four-state Dakota Access pipeline, which crosses 18 Iowa counties.

While members of both parties signed the letter, no signatures from Iowa's Congressional delegation were included.

In addition to nonviolent demonstrations across the nation — most notably in North Dakota near the Standing Rock Sioux reservation — opposition to Dakota Access included physical vandalism and trespassing on construction sites. In Iowa alone, hundreds were arrested for protesting on work sites.

"While we are strong advocates for the First Amendment, violence toward individuals and destruction of property are both illegal and potentially fatal," the letter stated.

Changes in legal posturing may come too late for those who broke the law fighting the Dakota Access pipeline, which went into operation this summer.

But law enforcement and elected officials have publicly warned about the long-lasting impacts of the nationwide protests, which have since snowballed into opposition of oil and gas pipeline projects from Florida to Oregon. Across the border in Nebraska, protesters are opposing the revived plan to build the Keystone XL pipeline. Nebraska regulators are expected to decide the fate of that project by November.

In addition to exploring possible terrorism charges, the Congressional correspondence asks if existing laws adequately arm the Department of Justice to "prosecute criminal activity against energy infrastructure at the federal level." It also specifically asks whether Sessions will charge those involved in a multi state effort to shut down pipelines in October 2016.

The GAIN coalition — short for Grow America's Infrastructure Now — applauded the Congressional effort. That group lobbied hard on behalf of Dakota Access pipeline builder Energy Transfer Partners, arguing that the pipeline would provide jobs and inexpensively and safely move energy across the country.

“Without strict enforcement of our nation’s anti-terrorism and other criminal laws, eco-terrorists will continue to be emboldened to destroy private property and threaten personal safety," said GAIN Coalition spokesman Craig Stevens in a statement. "We are already seeing too many incidents of eco-terrorism and vandalism hitting lawfully approved energy infrastructure projects across the country."

But pipeline opponents object to such characterizations.

"Terrorism is a really heated word and a very specific word in the American conscience right now," said Ed Fallon, a vocal pipeline opponent. "To apply that to folks — who even if their tactics might be questionable — folks who are concerned about protecting the planet, that’s going way too far."

Fallon, a leader of Bold Iowa, kept close watch over the arrests of pipeline protesters in Iowa: He estimates law enforcement across the state made some 400 arrests. Most of the trespassing charges resulted in fines of about $275, he said.

Most of those arrested were protesting peacefully, he said. But some were not: In July, two activists confessed to repeatedly damaging Dakota Access pipeline equipment, including burning at least five pieces of heavy equipment on the pipeline route in northwest Iowa's Buena Vista County.

Fallon disavows such tactics. But he fears that a hard line from federal prosecutors is an overreach that could end up stifling the First Amendment rights of nonviolent protesters.

"I think that's the risk that we run here if this pursuit is allowed to run its course," Fallon said.

The Congressional letter accuses protesters of using blow torches to burn holes in pipelines and promoting violence against oil and gas company employees. And it points to recent examples of protesters seeking to shut down pipelines by turning valves at pump stations.

For its part, the GAIN Coalition urged Sessions to take action on the issue: "Violence and vandalism is a violation of the law, even if it’s done under the cloak of environmentalism," Stevens' statement read.

The GAIN Coalition — formerly known as the MAIN Coalition — includes unions, chambers of commerce, manufacturing groups and oil and gas interests. The Iowa Association of Business and Industry is a member.

ABI President Mike Ralston said pipeline protests are one thing, but vandalism is just plain illegal.

"We always think the law should be followed," he said.

Still, he said he wouldn't necessarily label pipeline foes as terrorists.

"I had not thought of that characterization when I think of what happened," he said. " I do think it's wrong. Not only is it illegal, it's wrong. (But) I guess I hadn’t thought about characterizing it as terrorism."

Ralston said he didn't see a big need in Iowa to change how law enforcement responded to anti-pipeline activists.

"To the best of my knowledge, every case was handled well," he said. "There were legal ramifications for those who disobeyed the law. So yeah, I'm very satisfied with what happened in Iowa."