Thousands of Facebook users across the U.S. have been falsely "checking in" at the Standing Rock Indian Reservation in North Dakota after a viral message claimed that investigators were tracking protesters on Facebook.
Officials, however, say it's a hoax.
But some Native American activists still welcomed the check-ins as another form of showing support for the months-long protest against the Dakota Access Pipeline, proposed to run past tribal land on its route between North Dakota and Illinois.
The source of the message — which used "Randing Stock" as a code phrase so that users could locate each other — could not be verified by the Los Angeles Times.
"The Morton County Sheriff's Department has been using Facebook check-ins to find out who is at SR [Standing Rock] in order to target them in attempts to disrupt the prayer camps," said the earliest publicly traceable version of the post, shared by a Facebook user from North Carolina on Sunday. "
SO Water Protectors are calling on EVERYONE to check-in at SR to overwhelm and confuse them."
The message took off. Sympathetic Facebook users began checking in, while copying and pasting the message into their own profiles, like an email chain message.
Some law enforcement agencies have used social media in recent years to monitor activists — and, in some cases, used social media posts as evidence in criminal cases against protesters — but on Monday, the Morton County Sheriff's Department said the claim was a hoax.
"In response to the latest rumor / false claim circulating on social media we have the following response," the department said in a post on Facebook. "The Morton County Sheriff's Department is not and does not follow Facebook check-ins for the protest camp or any location. This claim / rumor is absolutely false."
Demonstrators have been at Standing Rock for months to protest the planned path of a pipeline that they say could desecrate tribal lands and put their drinking water at risk.
At least 141 people were arrested last week after hundreds of police officers in riot gear, flanked by military vehicles releasing high-pitched "sound cannon" blasts, tried to dislodge activists from the rough wildlands near the Cannonball River.
In a Facebook post, activists at the protest site's Sacred Stone camp said they didn't know where the message came from, but they said they appreciated it.
"We support the tactic, and think it is a great way to express solidarity," the group said, adding that it had "no doubt" law enforcement monitored social media.
The group added that the message's popularity on social media had provided a boost of much-wanted media attention.
"Our growing massive social media following plays a key role in this struggle," the group said in its Facebook post, urging supporters to engage in physical protests against fossil fuels and provide financial support.
"We have been ignored for the most part by mainstream media, yet we have hundreds of thousands of supporters from across the world. We appreciate a diversity of tactics and encourage people to come up with creative ways to act in solidarity, both online and as real physical allies."
The size of the protest camps along the Cannonball River has grown and shrunk over the months — from an estimated high of 5,000 protesters in the summer to around 1,200 now.
Follow me on Twitter: @mattdpearce
3:45 p.m.: This article was updated with background and comments by activists at the protest site's Sacred Stone camp.