Honduran migrants resting at a gas station in Zacapa, Guatemala. Photo: ORLANDO ESTRADA/AFP/Getty Images

A group of migrants, numbering somewhere between 1,500 and 2,000, set off from Honduras last Friday, crossed into Guatemala on Monday, and drew the ire of President Trump on Tuesday.

In one of 22 tweets sent Tuesday, Trump threatened to end all aid to Honduras, a deeply impoverished nation, if its citizens were allowed to continue their journey north.

The United States has strongly informed the President of Honduras that if the large Caravan of people heading to the U.S. is not stopped and brought back to Honduras, no more money or aid will be given to Honduras, effective immediately! — Donald J. Trump (@realDonaldTrump) October 16, 2018

Later Tuesday, he expanded the threat to include Guatemala and El Salvador, adding: “Anybody entering the United States illegally will be arrested and detained, prior to being sent back to their country!”

The so-called caravan, a loosely assembled group of migrants travelling by foot and bus, is the first to get Trump’s attention since last April, when he tweeted a similar threat to end aid to Honduras as a group of migrants worked its way north. That threat didn’t stop the caravan from reaching the U.S.-Mexico border, though by the time it did its numbers had dwindled from 1,200 to around 150.

The Central American countries on the wrong side of Trump’s threat appear to be taking it seriously. Guatemalan police attempted to blockade its border with Honduras Monday, but after a two-hour standoff, the group of migrants was allowed to pass.

Walking the 14km or so up to Esquipulas from the border with an estimated 2,500 people after #Guatemala backed down and police let the #Honduras migrant caravan pass. Here's a clip of people crossing, from earlier: pic.twitter.com/HWh3tKuzvU — Sandra Cuffe (@Sandra_Cuffe) October 15, 2018

After the caravan passed into Guatemala, authorities arrested the group’s spokesman, former Honduran congressman Bartolo Fuentes. He did not properly register with migration authorities, officials said, and would be deported back to Honduras.

“What Trump says doesn’t interest us,” Fuentes said before he was arrested. “These people are fleeing. These people are not tourists.”

With little to be done to bring back citizens, the Honduran Ministry of Foreign Affairs put out a statement encouraging them to return to the gang-riddled nation. We urge “the Hondurans taking part in this irregular mobilization not to be used by a movement that is clearly political,” the statement said.

Honduras’s attempt to comply with Trump’s wishes is understandable. It risks a lot if he follows through on his threat, as the L.A. Times reports:

The U.S. gave Honduras more than $180 million in aid in 2017 for a range of programs designed to improve security and combat poverty and drug trafficking, according to the Washington Office on Latin America think tank. Those funds are appropriated by Congress.

Cutting U.S. aid to Honduras could be counterproductive though. Last month, President Juan Orlando Hernandez said that such cuts would only make it harder to prevent migrants from packing up their lives and heading north.