The U.S. Border Patrol this week reportedly told Texas landowners along the U.S.-Mexico border to prepare for a possible influx of "armed civilians" on their property as the migrant caravan moves closer to the U.S., a report said.

The Associated Press reported that these civilians say they intend to support the National Guard and Border Patrol to prevent the illegal migrants from crossing into the U.S.

But some see the move as a negative, arguing that the armed civilians' presence would add even more tension should there be a confrontation.

Three activists told the AP they were going to the border or organizing others, and groups on Facebook have posted warnings about the caravan. One said it was “imperative that we have boots on the ground.” Another wrote: “WAR! SECURE THE BORDER NOW!”

President Trump tweeted on Monday, "This is an invasion of our Country and our Military is waiting for you!"

Shannon McGauley, president of the Texas Minuteman militia, told the AP that he already has members at three points of the state's border and expects 25 to 100 more people to arrive in the coming days.

Militia members and volunteers patrolling the border is a practice that has been in place for decades. Usually, the civilians patrol the border and look out for illegal border crossers. Once they spot a trespasser, the civilians usually contact the Border Patrol to apprehend them. (The Border Patrol is the law enforcement branch of U.S. Customs and Border Protection, part of the U.S. Department of Homeland Security.)

This practice has not been without problems. In 2009, a militia member Shawna Forde killed two U.S. citizens, Raul and Brisenia Flores, during a raid on what she thought was a drug house near the border in Arizona.

Residents in a small Arizona town have posted signs saying these militias are not welcome. One resident told the Arizona Republic that she has an anti-militia sign in her yard because she “wants everybody to be aware that we do not want the militias.”

People from other states have raised money to assist the militias with supplies and equipment. The militias are expected to bring guns and tactical gear, such as bulletproof vests.

Marianna Trevino Wright, a South Texas resident, told the Yucatan Times that she is concerned about the arrival of militias.

"We go about our business here every day in a peaceful manner," she told the paper. "The idea that we could be invaded not by illegal immigrants but by militia groups … is regrettable, and it will end badly."

"We go about our business here every day in a peaceful manner. The idea that we could be invaded not by illegal immigrants but by militia groups … is regrettable, and it will end badly." — Marianna Trevino Wright, a South Texas resident

The report said it is unclear how many militia members will arrive at the border to face the first caravan, which is currently estimated to include some 4,000 people — mostly citizens of Honduras — who seek to enter the U.S. to improve their economic situation.

The caravan is currently about 1,000 miles south of the border and estimated to be more than a week from arriving there.

President Trump has announced the deployment of 5,000 troops along the border, in a move that has been criticized by some as a pre-election stunt.

Trump told Fox News on Monday that the migrants are "wasting their time" and vowed, "they are not coming in."

Trump spoke to "The Ingraham Angle" hours after the Pentagon announced it would deploy troops to the southern border in what the commander of U.S. Northern Command described as an effort to "harden the southern border" by stiffening defenses at and near legal entry points.

"When they are captured, we don't let them out," Trump told host Laura Ingraham. "We're not letting them out ... We're not catching, we're not releasing. ... We're not letting them into this country."

Fox News' Samuel Chamberlain and the Associated Press contributed to this report.