WASHINGTON • President Donald Trump has threatened to deploy the military and close the southern US border if Mexico does not halt a caravan of Central America migrants heading north, raising the risk of huge disruptions to trade.
Stretching almost 3,200km, the US-Mexican border is one of the busiest in the world, processing thousands of commuters daily and much of the half a trillion dollars of annual trade between Mexico and the United States.
"I must, in the strongest of terms, ask Mexico to stop this onslaught - and if unable to do so I will call up the U.S. Military and CLOSE OUR SOUTHERN BORDER!" Mr Trump wrote on Twitter on Thursday.
Several thousand Honduran migrants moved this week through Guatemala, and some were trying to cross to Mexico on Thursday, local media said. Some hope to eventually enter the US to escape violence and poverty.
Mexico's government said it had sought assistance from the United Nations refugee agency to deal with migrants claiming refugee status at Mexico's southern border.
Yesterday, US Secretary of State Mike Pompeo was to meet Mexico's officials including outgoing President Enrique Pena Nieto, Foreign Minister Luis Videgaray and Mr Marcelo Ebrard, the designated foreign minister of President-elect Andres Manuel Lopez Obrador.
Mr Lopez Obrador, who takes office in December, said in the northern city of Saltillo on Thursday that he believed "an agreement can be reached" on the migration issue. "We're going to take care of our relationship with the US government," he said. "It's very important to have a relationship of friendship."
Mr Trump told a political rally in Montana on Thursday he wanted "to thank the Mexican government because they are stopping it hopefully before it ever gets to Mexico".
Mr Videgaray said his government had asked the UN High Commissioner for Refugees (UNHCR) to help process the migrants to guarantee transparency, and so that Mexico could cope with a "higher volume of requests".
"Later on, UNHCR could help the Mexican government to find places to settle (migrants) inside or outside Mexico for those granted refugee status, but that hasn't been defined with UNHCR yet," he said.
In the caravan, Central American migrants hiked from Honduras through muddy jungle and residential streets, some toting babies along with backpacks, Reuters images show.
In Guatemala City, where migrant shelters filled with people, waves of people departed at daybreak on roads leading to Mexico. The nearest border is about 177 km away.
There are no official estimates of the size of the group.
Illegal immigration is likely to be a top issue in the Nov 6 congressional elections in the US and Mr Trump claimed migrants in the caravan were being used by his political opponents. "A lot of money has been passing to people to come up to try and get to the border by Election Day," he said, without giving evidence.