CANNON BALL, N.D. — Tears pooled in the corners of Leomana Turalde’s eyes as he stared down an icy stretch of North Dakota highway at a military-grade armored truck parked behind concrete barricades.

The distance of a hundred yards seemed like a portal between two worlds that have defined much of his life.

Turalde is a Native Hawaiian hula dancer from the Big Island who was making his first trek to the Standing Rock Sioux reservation to protest the Dakota Access oil pipeline.

He’s also a Marine Corps veteran who served in Iraq as part of a reconnaissance unit. The MRAP (mine-resistant ambush protected) vehicle and armored Humvees parked atop the snow-covered hills brought back unwelcome memories of war.

“Fuck,” Turalde said. “This makes me want to cry.”

Turalde was one of hundreds of veterans who arrived Saturday at the Oceti Sakowin Camp, which has become the frontline in the battle over the pipeline and the rights of the Standing Rock Sioux, many of whom have hunkered down for months in an effort to stop the project from being built through their ancestral lands.

Up to 2,000 veterans are expected to arrive by Sunday as part of a three-day protest in support of the tribe. They have vowed to act as human shields for demonstrators, many of whom have been subjected to harsh police tactics, including tear gas, rubber bullets and a water cannon dousing in below-freezing temperatures.

Turalde wore an aloha shirt underneath his thick winter jacket. His pants were patterned camouflage.

When he marches in protest of the pipeline in the coming days, he said he’ll don his formal Marine Corps uniform, including the medals.

Turalde almost didn’t make the trip from Hawaii to North Dakota. He’s a University of Hawaii student now, and has final exams in a week. But he said he watched viral videos of native protesters being hosed with water by the Morton County Sheriff’s Department and shot at with rubber bullets.

“I didn’t go to Iraq, I didn’t lose a lot of friends in war so that we could do this to our own people,” Turalde said. “That’s not what I fought for and that’s not what my friends gave their lives for.”

The tribe is worried that the 1,172-mile oil pipeline — much of it already constructed — will threaten its Missouri River water source and desecrate culturally sensitive lands that include burial grounds. Tribal members also oppose the exportation of a fossil fuel source that contributes to global warming and other environmental hazards.

The U.S. Army Corps of Engineers, which manages the land the Oceti Sakowin Camp sits on, has already approved construction of the pipeline. The federal agency also issued a Monday deadline for demonstrators to evacuate the camp or risk prosecution for trespassing. Government officials have said they will not forcibly remove anyone.

On Saturday, a steady stream of vehicles poured into the Octei Sakowin Camp. There was also a constant flow of cars and trucks into a neighboring camp on the Standing Rock reservation, outside of the zone that officials want evacuated.

The sound of chain saws and hammers drowned out the prayers and drumbeats that previously dominated the audial landscape. New tents and teepees were erected, as were yurts and other large housing structures that were built to withstand the brutal Upper Midwestern winter known for snow and sub-zero temperatures.

Private helicopters hummed overhead, surveying the growing community. Police officers were perched on the hilltops surrounding the camp and at the barricade at Backwater Bridge, the site of some of the most violent confrontations the public has witnessed during the months-long occupation.

With the veterans’ arrival, another confrontation could be on the horizon, event though the Morton County Sheriff’s Department held a press conference Saturday to say it would remove its blockades on the bridge in an attempt to de-escalate the tension.

U.S. Rep. Tulsi Gabbard of Hawaii is in North Dakota to take part in the veterans’ protest. Gabbard is a major in the Army National Guard and a combat veteran.

The congresswoman appeared at a gathering of veterans and protesters Saturday night about 30 miles away at Sitting Bull College in Fort Yates, The Huffington Post reported.

Her plans for Sunday were unclear.

Hawaii resident Michael Kyser Jr. said the fact that Gabbard is here at all says a lot about her character. Kyser, like many other islanders who have traveled to Standing Rock, has a history of fighting for native rights. He was one of many Native Hawaiians who camped atop Mauna Kea on the Big Island to oppose the construction of the Thirty Meter Telescope.

Kyser said he hopes that Gabbard’s presence means that she takes indigenous concerns seriously, and that she will apply that to other issues facing her own constituency in rural areas populated by Native Hawaiians.

“She hasn’t really played a big role in stuff happening with the Hawaiian people back home,” Kyser said. “Hopefully this will be an eye-opener for her. I know she’s trying to do her best.”

But Kyser also worries about the influx of newcomers at Standing Rock, particularly those who are not necessarily tied to a Native American tribe. He’s been here since August, and has become a recognizable presence if only because he greets everyone with a smile and a booming, “Aloha!”

He said there’s a level of cultural sensitivity and respect that must be maintained for the protest to be effective. The last thing he wants to see is someone have an emotional outburst that leads to a violent reaction from police.

“As more people came that are not native to the land here it kind of changed the vibe because people don’t know how to act in a situation like this,” Kyser said. “Although it’s a peaceful, prayerful movement, most people don’t know how to be in that state and not react to what’s happening on the other side of that line.”

“You can’t have two negatives,” he said. “Two negatives in the math world makes a positive. But it doesn’t make a positive here in this world.”