The US military will deploy 5,000 troops to the southern border - up from initial estimates of 800, according to the Wall street Journal, citing US officials. The troops will be sent to Texas, Arizona and California as Central American migrant caravan makes its way north through Mexico.

Defense Secretary Jim Mattis told reporters Sunday that the military has already started to deploy countermeasures to the southern border, following weekend reports that Mexican police had abandoned their own blockades as a massive Central American migrant caravan continues their march north, reports AP.

On Monday, President Trump warned the caravan, tweeting: "Many Gang Members and some very bad people are mixed into the Caravan heading to our Southern Border. This is an invasion of our Country and our Military is waiting for you!"

Many Gang Members and some very bad people are mixed into the Caravan heading to our Southern Border. Please go back, you will not be admitted into the United States unless you go through the legal process. This is an invasion of our Country and our Military is waiting for you! — Donald J. Trump (@realDonaldTrump) October 29, 2018

Pentagon is installing jersey barriers ahead of the troop deployment.

Jersey Barrier

The additional troops will provide logistical and other support to the Border Patrol, and will bolster the efforts of the approximately 2,000 National Guard forces already there. The new forces are expected to provide logistical assistance such as air support and equipment, including vehicles and tents. National Guard troops routinely perform those same functions, so it is not clear why active duty forces are being used. -AP

Mattis's comments come amid a vow by Homeland Security Secretary Kirstjen Nielsen that the caravan "is not getting in."

"My general message to this caravan is: Do not come," Nielsen said. "You will not be allowed in. ... There is a right way to immigrate to the United States," she continued, "and this is not it."

RT RealSaavedra: DHS Secretary Kirstjen Nielsen: "My general message to this caravan is do not come. You will not be allowed in." pic.twitter.com/UyKeHCCUkb — Cassandra Payne (@CassieMAGA2016) October 28, 2018

On Sunday night, Fox News initially reported that just 800 soldiers would be deployed to the border to provide "logistical support," which includes providing vehicles and tents for the Border Patrol.

The caravan of roughly 7,200 migrants is around 1,000 miles from the closest US border crossing, and is becoming yet another flashpoint over President Trump's immigration policy less than two weeks before the key November 6 midterm elections. According to Fox, the group is traveling at around 30 miles per day since leaving Honduras.

Vice President Mike Pence warned this weekend that the caravan was being funded by outside, leftist groups, citing intelligence he says was provided by foreign partners along with a telephone call with the President of Honduras.

"What the president of Honduras told me is that the caravan was organized by leftist organizations, political activists within Honduras, and he said it was being funded by outside groups, and even from Venezuela," Pence told Fox News in an interview late Friday in Yuma, Arizona. "So the American people, I think, see through this – they understand this is not a spontaneous caravan of vulnerable people." -Fox News

President Trump, meanwhile, has levied harsh criticism at Honduras, Guatemala and El Salvador for not stopping the caravan, and even threatened to cut off aid last week in retaliation. Trump has also claimed that "criminals and unknown Middle Easterners" are among the migrants, while Homeland Security said last week that "gang members" and those with "significant criminal histories" are also traveling with the caravan.

🚨BREAKING NEWS



FOX just interviewed a member of the caravan that admitted he was a convicted murderer and is traveling with the mob to come back into the United States!



This is who the radical left wants in your Country. VOTE THEM OUT NOVEMBER 6Th!#VoteRed #NoSocialism #MAGA pic.twitter.com/x7yJaFHeQo — Cindyseestruth (@cs00582scs) October 28, 2018

Over 100 Mexican officers allowed the caravan to cross a bridge they had barricaded following outrage from Mexico's National Human Rights Commission, which told police that the rural stretch of highway they were blocking had no shade, toilets or water for the migrants.

Police boarded buses and headed further down the highway, while migrants cheered and vowed to trek all the way to the U.S. border. Mexican President Enrique Pena Nieto launched a program on Friday dubbed "You are home," which promises shelter, medical attention, schooling and jobs to Central Americans who agree to stay in the southern Mexico states of Chiapas or Oaxaca. Police commissioner Benjamin Grajeda said that authorities only blocked the highway Saturday to tell people about the government's offer. "Here in this truck right now you can get help," he said. -Fox News

Thousands of migrants rejected Mexico's offer for asylum Friday night, however some said they were willing to discuss the issue once they reach Mexico City. If those discussions don't result in the caravan stopping, US forces await at the border.