Police are investigating a new incident of pipeline sabotage in which an activist poured corrosive material into sections of pipe destined for a crude oil pipeline in southern Ontario.

The sabotage is the just latest attempt to protest oil infrastructure through vandalism, although it is one of the more aggressive — and potentially dangerous — actions.

An anonymous poster is taking credit for drilling holes and pouring corrosive material into sections of stored pipe meant for Enbridge’s Line 10 pipeline. Currently under construction, the project involves expanding 35 kilometres of the line, installed in 1962, allowing it to carry up to 74,000 barrels of oil per day.

“Back when Enbridge started shipping in pipeline segments for their Line 10 expansion, we started sabotaging them,” the poster braggs on Anarchist News. The poster describes going on long, moonlit strolls through freshly-dug pipeline trenches. “Wherever we felt the urge, we drilled various sized holes into pipeline segments while spilling corrosives inside others.” The post includes a How-To guide for sabotaging a pipeline.

Hamilton Police confirmed they are investigating an incident this month in which an activist tampered with Enbridge’s Line 10 pipeline. An Enbridge representative confirmed to VICE News they are the same incident.

“Tampering with stored pipe was discovered as part of Enbridge’s rigorous inspection process,” Enbridge representative Michael Barnes said in a statement. “We treat these situations very seriously and will support the prosecution of anyone involved. Safety of the public, the environment and our workers is our top priority at Enbridge.

“Pipelines are no different than power lines or railway lines and tampering with energy infrastructure puts people and the environment at risk.”

The National Energy Board, the regulator for the project, told VICE News that Enbridge does not have a responsibility to report criminal activity on its pipeline to the NEB.

“For every dollar you pursue from Indigenous Nations or individuals for defending their territories, we aim to cost you ten.”

The poster to Anarchist News claims to have done so “in solidarity with the Indigenous peoples of this area.”

The post continues: “To Enbridge: you’re gonna want to replace every last section of Line 10 that’s been laid out so far. We say this because we care for the environment and don’t care about you — so take it seriously.”

Enbridge pipelines including Lines 9 and 10 have been magnets for pipeline activism in southern Ontario and Quebec. Activists have turned off pipeline valves along Line 9 and locked themselves to the pipeline. Others have posted how-to videos of how to shut down a pipeline. In Alberta earlier this year, vandals used construction equipment to dig up part of a non-functioning pipeline.

While most anti-pipeline vandalism in Canada generally turned off pipelines, or targeted non-active lines, others were higher risk. Wiebo Ludwig, an Alberta eco-activist, was convicted of blowing up and sabotaging oil wells throughout the 1990s, and arrested again following a string of bombings between 2008 and 2010. Law enforcement and regulators have warned sabotaging an operating pipeline can be dangerous, as they can explode and leak.

The activist claims to have acted “in solidarity with the Indigenous peoples of this area” — but First Nations who oppose the pipeline say the activist may have done environmental damage.

Some members of Six Nations have opposed the expansion project. Six Nations member Todd Williams has been protesting the pipeline because he contends it is on the traditional hunting ground of Six Nations of the Grand River, the largest First Nation in Canada. He says the British were granted access to the territory for trade and to build forts under the Fort Albany Treaty of 1701, and was never ceded. He says it is harmful to the environment and nearby archaeological sites.

The poster nods to the protests against the line, writing: “For every dollar you pursue from Indigenous Nations or individuals for defending their territories, we aim to cost you ten.”

But Williams, who has been protesting Line 10 by setting rabbit traps on work sites, says he’s not cool with activists using corrosive materials to sabotage the pipeline.

“Now there’s an environmental concern there.”

“Now there’s an environmental concern there,” Williams told VICE News. “And that needs to be cleaned up properly.” Williams is facing $18,000 in legal fees after he interfered with an injunction and the court sided with Enbridge.

He didn’t condemn the activists for drilling holes into pipeline, saying “it’s not as environmentally dangerous as the corrosive material.” But he did take aim at Enbridge, saying they should have better security on site.

He questioned whether the anonymous poster was truly acting in solidarity with Six Nations people, or whether they had their own agenda.