Hawaii Congresswoman Tulsi Gabbard is expected to join as many as 2,000 veterans from across the country at the Standing Rock Sioux Reservation in North Dakota to protest an oil pipeline that tribal leaders say threatens their water supply and cultural heritage sites.

Gabbard, a major in the U.S. Army National Guard, said in a statement Tuesday that she will take part Sunday in the Veterans Stand for Standing Rock protest, which warns attendees through its Facebook page to bring body armor, gas masks and earplugs so that they can protect themselves against police actions.

The veterans are planning to be on the site from Sunday through Dec. 7.

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The protests, which have been going on for months, have intensified over the past several weeks as temperatures have dipped below freezing. Hundreds of demonstrators have been arrested or injured during clashes with police and private security, who have used tear gas and guard dogs.

State and federal officials have demanded that the demonstrators, many of them Native American, leave the area. The local sheriff said Tuesday he will attempt to cut off access to the protest camps.

Gabbard is one of the most high-profile attendees listed on the Veterans Stand for Standing Rock event page. Others include Wesley Clark Jr., the son of retired Army Gen. Wesley Clark, and Michael Wood Jr., a former Baltimore police officer who has been outspoken about police practices, including the excessive use of force.

“I’m participating in the Dakota Access Pipeline protest because of the threat this project poses to water resources in four states serving millions of people,” Gabbard said in her statement. “Whether it’s the threat to essential water sources in this region, the lead contamination in Flint, Michigan, or the threat posed to a major Hawaii aquifer by the Red Hill fuel leak, each example underscores the vital importance of protecting our water resources.”

The congresswoman added that protecting water should not be looked at as a partisan issue and called on President Barack Obama to halt the $3.8 billion project, which is funded by Dallas-based Energy Transfer Partners.

Gabbard was critical of the company’s safety record, as well as that of Sunoco Logistics, which will take over operations of the Dakota Access Pipeline once it is completed. It is expected to pump up to 570,000 barrels of crude oil a day from North Dakota to Illinois.

Gabbard said Energy Transfer Partners “has a history of serious pipeline explosions” over the past decade that have resulted in injury, death and property damage. She also noted that Sunoco Logistics has had more than 200 oil spills over the past six years, which the congresswoman said was more than its competitors.