He also threatened to withdraw aid from migrants' home countries if they didn't put a stop to the mass migration.
The key questions: Will Mexico let the migrants in?
Some hung out their wet clothes to dry on railings and tree branches, while looked for a way to exchange their Guatemalan quetzales for Mexican pesos. In April, he said in a meeting with foreign leaders that the U.S.is "going to be guarding our border with our military".
Honduran migrants remove a barrier at the Guatemala-Mexico worldwide border bridge.
A bridge over the river marks an official crossing point.
However, as USA Today notes, it is "not entirely clear" what Honduran President Juan Orlando Hernandez can do to turn the migrants back now that they are on Guatemalan soil. By the afternoon, one group had broken through a fence and crossed a bridge into Mexico, where they met with a group of 50 Mexican police wielding riot gear and pepper spray. Those who do so will be held "at a migratory station" for up to 45 business days.
Marcelo Ebrard, who is set to become foreign relations secretary when President-elect Andres Manuel Lopez Obrador takes office December 1, said Trump's tweets need to be understood in the context of the upcoming USA midterm elections.
In April, Mexican immigration officials had some success in dispersing a smaller caravan by processing many who chose to seek refugee status in Mexico, but some did continue on to the USA border.
Arizona Border Patrol agents for weeks have been overwhelmed by the arrival of large numbers of Central American migrants travelling in families. A complicated mix of pressures are weighing on Mexican officials as they decide how to handle the matter.
Videgaray says that "for the Mexican government it is essential first to respect and protect the human rights and fundamental dignity of all of the migrants and to do so under a logical and humanitarian and respectful treatment".
Beyond that, this situation catches Mexico at a odd time.
In another, he suggested that the "onslaught" of immigrants could undermine a recently announced reworked trade deal with Mexico and Canada, writing that immigration is "far more important to me, as President, than Trade". "Hopefully Mexico will stop this onslaught at their Northern Border", Trump tweeted.
If Trump pulls out of the trade deal or closes the border, there would be major economic implications for both countries.
The nonprofit also noted that Prensa Libra, a Guatemalan newspaper, "published an in-depth piece on the inner workings of an worldwide human smuggling network that moves migrants from Afghanistan, Pakistan, India, Nepal and Bangladesh to the U.S".
Thousands of people and goods legally cross the US-Mexico border daily.
It's also about Mexican emigrants living overseas, many of whom are undocumented.
Hundreds of federal police in riot gear fanned out on the global bridge in Suchiate, on the Mexican-Guatemalan border, as the caravan of several thousand Honduran migrants trekked toward the crossing.
Mexican President Enrique Peña Nieto has partnered with the United States in the past on immigration-related issues.
The Associated Press reports that many migrants do not have passports and have been using national ID cards, which allow them to travel within Central America.
In the caravan, Central American migrants hiked from Honduras through muddy jungle and residential streets, some toting babies along with backpacks, Reuters images show. "Anyone who wants to work in our country will have help, will have a work visa", he pledged.
"We're going to get in!"