The president of a major labor union sent a blistering letter to its members on Wednesday calling out other unions, dubbing them "bottom-feeding organizations" for their opposition to a controversial oil pipeline project.
There are more than 1,100 members of the Laborers International Union of North America (LIUNA) working construction jobs on the Dakota Access pipeline, wrote Terry O'Sullivan, the union's president.
The pipeline has drawn opposition from environmentalists and Native American tribes in North Dakota, and intense, occasionally violent protests from left-wing anti-energy activists that O'Sullivan derided as "THUGS."
However, he reserved his most pointed criticism for a group of labor unions that have publicly backed those activists and the larger anti-pipeline environmental movement.
"They are a group of bottom-feeding organizations that are once again trying to destroy our members' jobs," O'Sullivan wrote.
He called out five "job-killing" unions by name: the Communications Workers of America (CWA), National Nurses United (NNU), the Amalgamated Transit Union (ATU), the American Postal Workers Union (APWU), and the Service Employees International Union (SEIU).
"LIUNA will not forget the reprehensible actions and statements against our members and their families from the five unions listed above," O'Sullivan wrote.
"Brothers and sisters, for every ACTION there is a REACTION, and we should find every opportunity to reciprocate their total disrespect and disregard for the health, safety, and livelihoods of our members."
None of the five unions mentioned returned requests for comment by press time.
O'Sullivan made sure to express sympathy for civil disobedience and peaceful protest in his letter. But he said his union would draw the line at "aggressive tactics that threaten the safety of construction workers, public safety officers, and protesters themselves."
Dakota Access pipeline protests have turned violent over the last two months as tensions at pipeline construction sites escalate. Arsonists caused about $2 million in damage to construction equipment last week.
The sheriff of Morton County, N.D., where many of the protests have occurred, said his officers have encountered "incidents and reports of weapons, of pipe bombs, of some shots fired."
"In essence, these protesters are acting like thugs," O'Sullivan wrote.
His union has been highly critical of environmental opposition to other energy projects, most notably the Keystone XL pipeline, which was shot down by the Obama administration after it became a rallying cry for anti-fossil fuel groups.
A number of unions singled out in O'Sullivan's Wednesday letter also opposed Keystone. He claimed their opposition has nothing to do with Dakota Access specifically, but is rooted in opposition to any and all oil pipelines.
"Some of our so-called brothers and sisters in the trade union movement have abandoned solidarity with the working class and are instead throwing in with environmentalists who have co-opted the tribes in their effort to fight pipelines," O'Sullivan wrote.
He dismissed protesters' concerns as overblown or factually inaccurate.
"Much of the opposition to the Pipeline is based on misinformation," he wrote. "The facts are on our side, yet in the past month, we have witnessed vocal opposition from groups, including some self-righteous unions, who know little about the project and have no job equity in it."
Update: After publication, National Nurses United and the American Postal Workers Union both sent emails declining to address O'Sullivan's comments.