The migrants had already made a gruelling 65-kilometre trek from Juchitan, Oaxaca, on Thursday, after they failed to get the bus transportation they had hoped for.
It was unclear whether the restrictions Trump was expected to propose would apply only to those traveling in the caravans or extend to all people trying to enter the country.
Trump also said his administration will "catch" immigrants but no longer "release" them.
Trump spoke during a presentation of his controversial policy on cracking down against what he says is uncontrolled illegal immigration.
With or without the Mexican government's help, it remained unclear how many migrants would make it to the US border; many days of scorching heat, constant walking, chills, rain and illness have taken their toll.
Trump had yesterday announced that he plans to automatically deny asylum to migrants who try to enter the USA illegally between ports of entry.
The official spoke on condition of anonymity to provide details not yet released.
In any case, Fox News also reports that there was some confusion over whether the caravan was heading for the California border or for the much closer border crossing in McAllen, Texas.
Writing at Task and objective, retired Col. Paul Yingling, who commanded USA troops in Iraq, cut right to the chase.
After three grueling weeks walking along highways and hitching rides, thousands of Central American migrants traveling in a caravan through southern Mexico were told Friday that they would soon be leapfrogging ahead to the nation's capital in buses only to have their hopes dashed nearly immediately when the offer was pulled.
The migrants in the caravans are mostly from Honduras, where it started, as well as El Salvador and Guatemala.
James Stavridis, a retired Navy admiral and former head of the US Southern Command, said the troops should be preparing for combat and other missions, "not monitoring a peaceful border" for the arrival of a migrant caravan of several thousand people on foot, still about 900 miles (1,450 kilometres) away.
Last week officials indicated 800 to 1,000 troops might be sent.
Trump made the comments Thursday in a speech on immigration.
Trump spoke directly to the mostly Honduran members of the caravan in the tweet, saying: 'Please go back, you will not be admitted into the United States unless you go through the legal process. On Monday, they announced that about 5,200 were being deployed.
Trump has rejected the idea he has been "fearmongering" and using the issue for political purposes, but his escalating rhetoric in the final days of the campaign season calls that denial into question.
He said some of the migrants in the caravans threw stones at Mexican police and soldiers.
It remained to be seen if the group would stick together and continue employing the "strength in numbers" strategy which has enabled them to move through Mexico together and inspired subsequent migrant caravans to try their luck.
It was reminiscent of the infamous "Willie Horton" ad used against Democratic presidential candidate Michael Dukakis in 1988 and condemned as racist. "The gunman who assassinates people on the Sabbath, ." he said, speaking to several USA news stories from last week. It adds: "Democrats let him into our country..."
His forward runs were just as unsafe to Chelsea as to the opponents; both visiting goals came from the space vacated on his flank. Predicted Derby County XI: Carson; Bogle, Tomori, Keogh, Forsyth; Wilson, Huddlestone; Waghorn, Mount, Lawrence; Nugent .
The voice on the call impersonated Oprah Winfrey , the billionaire media titan who came to Georgia on Thursday to support Abrams . The race between Kemp and Democrat Stacey Abrams has drawn wide national attention.
Without Mr Peever's resignation sidelined players Steve Smith, David Warner and Cameron Bancroft have little chance of returning. David Peever, CA chairman, said some good would come from the 42 recommendations in the report .
When he refused, the woman became enraged and hit him with her mobile phone before the driver lost control of the vehicle. However, Liu did not get off and later asked the driver to stop the bus when she realised she missed her destination.
The boys' bodies were wrapped in Palestinian flags and carried by mourners who shot in the air as they chanted "God is Great". Aisha Abu Daher said her 14-year-old son Abdel-Hamid had "nothing to do with resistance", referring to the militant factions.
Trump reiterated that he wanted to set up "tent cities" to hold people coming to the USA , including those seeking asylum. The military troops are meant to assist the border patrol, not engage directly with migrants, several officials said.
Verstappen was clearly frustrated by the result, bumping the second-place board as he arrived on the start-finish straight. The rivalry within the Red Bull ranks has not escaped Vettel's attention either.
Trump, Xi upbeat on ending trade war
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Golden Tate Traded To Eagles
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Nehmeh in breast cancer awareness drive READ MORE
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Germany’s governing parties punished in state election
Carsten Brzeski, an economist at ING-DiBa in Frankfurt, said Merkel's move "holds the potential for positive developments". The debacle followed a battering in a state election in Bavaria two weeks ago for the CSU and the Social Democrats.
Trump says birthright citizenship will be ended
However, White House lawyers expect to work with the Justice Department to develop a legal justification for the action. Trump wrote: "Harry Reid, when he was sane, agreed with us on Birthright Citizenship! ".
Federer claims 99th ATP title with Basel triumph
Federer's next opponent is seventh-seeded Daniil Medvedev , who beat fourth-seeded Greek Stefanos Tsitsipas 6-4, 3-6, 6-3. Second-seeded Kevin Anderson of South Africa led Croatian No. 6 Borna Coric 7-6 (2), 1-2 when Coric retired.
Sloane Stephens v Karolina Pliskova — WTA Finals
Osaka has had a whirlwind time since her stunning win over Serena Williams in a controversial US Open final. Serving for her place in the final, Svitolina saved two break points before shutting Bertens down.
Now, OnePlus 6T comes to India starting at Rs 37,999
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Here’s What’s New in iOS 12.1, Available Today
The update is still just as fast as iOS 12, so you really don't have to worry about performance degradation here. In addition to the built-in physical SIM, as of iOS 12.1 you can add a second line to your phone via an eSIM .