Construction equipment has moved into place to erect a looming border barrier in southern Texas in the middle of a butterfly refuge, whose operators are furious that their land has been seized and environmental regulations ignored.

The barrier is being erected along a levee of the Rio Grande in the border town of Mission.

The 18 feet of steel bollards on top of an 18-foot concrete wall will cut off 70 percent of the 100-acre National Butterfly Center closest to the river, refuge executive director Marianna Trevino-Wright told HuffPost. The barrier will be two miles from the actual border, so gates will be built to allow Texans access from one part of America to another, she said.

“This has nothing to do with a levee, nothing to do with the environment,” Wright said. “This is tactical. It’s going to be guarded by paramilitary personnel.”

Some 35,000 people a year visit the butterfly center, which has as many as 200 species of butterflies in a wildlife area that will be devastated by bulldozing and disrupted by vehicle traffic, bright lights, garbage and increased human activity, Wright complained. The wall will trap some animals on the river side during floods, and those on the other side away from water they need to survive.

As construction equipment was unloaded Monday a group of about 35 local tribal members marched in protest, the San Antonio Express-News reported.

“I didn’t expect it this soon,” Juan Mancias, tribal chair of Carrizo Comecrudo, told the newspaper. “There’s a constant uneasiness.”

Congress approved money for the barrier in last year’s federal budget, but it was pointedly not to be used to construct President Donald Trump’s wall — only for fencing or levees. The final product, however, looks suspiciously similar to an image he has tweeted of a version of his imagined wall.

Federal law passed in the wake of 9/11 allows the Department of Homeland Security to bypass environmental regulations for national security — a right the Supreme Court has let stand in a related case. The center launched a GoFundMe page, however, to continue a legal fight.

Construction, supervised by the department of U.S. Customs and Border Protection, is expected to begin within days.

Wright complained that there was no notice when trucks first came onto the property in the summer of 2017, in the early months of the Trump administration, to clear brush and cut down trees without permission — long before any allocation of money for the barrier.

As of Monday morning the federal government had offered no compensation for seizure of center land needed for the barrier and adjacent paved enforcement zones, Wright said.

Environmental waivers will also allow barrier construction to cut through the Bentsen-Rio Grande Valley State Park and some private property. Construction was also slated for the Santa Ana National Wildlife Refuge, though the refuge was ultimately spared after intense public backlash.

Wright told HuffPost that a border official told her the Trump administration is beginning its barrier construction in Texas through environmental sites because it’s the “path of least resistance.” That strategy won’t immediately trigger outrage from large numbers of private property owners whose land will also be confiscated.

U.S. Customs and Border Protection could not immediately be reached for comment. The agency claims on its website, however, that’s it’s “committed to environmental and cultural stewardship while performing our core missions of border security.” Department of Interior officials, however, have largely ignored wildlife experts’ concerns about the ecological devastation of a border wall.

Rep. Will Hurd (R-Texas), whose congressional district includes 820 miles of the southern border, is opposed to Trump’s wall. He estimates that the federal government could seize land from as many as 1,000 property owners in his district alone to build a wall. “There’s a thing in Texas we care about called private property rights,” Hurd has said.

He also noted that more than a million acres might be ceded to Mexico to build a wall, depending on natural physical barriers and which side of the Rio Grande the wall would be constructed. In the case of Mission, the barrier is going up on the American side.

Hurd believes border surveillance using radar and cameras, and a careful examination of what’s being done and what works is a far more rational approach to take.

All nine representatives who represent border areas in Texas, Arizona, New Mexico and California oppose the wall, but Hurd is the only Republican. Only two senators in those states — Sen. Ted Cruz (R-Texas) and Sen. Martha McSally (R-Ariz.) — support the wall.

CORRECTION: A previous version of this story said barrier construction was slated for Santa Ana National Wildlife Refuge. That construction is no longer planned.