(CNN) President Trump hasn't minced words in his tweets over a new migrant caravan heading for the United States.

Guatemala, Honduras and El Salvador were not able to do the job of stopping people from leaving their country and coming illegally to the U.S. We will now begin cutting off, or substantially reducing, the massive foreign aid routinely given to them.

All told, US aid planned for those countries in fiscal year 2019 adds up to more than $180 million.

That's already notably less than amounts pledged in past years -- and far less than the nearly $18 billion the World Bank estimates those countries received from migrants who sent money home last year.

Still, threatening to cut aid is a high-profile way for the United States to wield its global influence.

Here's a look at foreign aid spending that's planned for the next year in the countries connected to the caravan -- and some of the things it pays for:

Honduras

A caravan of Honduran migrants began forming Saturday and reached Guatemala's border on Monday.

A US government website that tracks foreign aid spending clearly states an underlying goal : improving conditions in Honduras so people won't migrate. "U.S. foreign assistance plays a critical role in supporting Honduras' development as a safe, democratic, and prosperous nation that offers hope to Hondurans so they see their future in Honduras and not elsewhere," the website says.

Aid from the US: $65.8 million

What it pays for: Aid to Honduras and other Central American countries Aid to Honduras and other Central American countries aims to promote prosperity and regional economic integration, enhance security and promote improved governance , according to the State Department. Among things it's funded in Honduras: rural development projects, reintegration for returning migrants and youth programs.

Guatemala

Police in Esquipulas, Guatemala, blocked the caravan for nearly two hours on Monday, before ultimately letting the group pass.

Of all the countries in Central America, Guatemala is set to receive the most foreign aid from the United States this year. Guatemalans also make up the largest number of family members -- and the largest number of unaccompanied minors -- apprehended after illegally crossing the US border, according to US Customs and Border Protection . And it's become the top destination for US deportation flights

Aid from the US: $69.4 million

What it pays for: Aid to Guatemala addresses "high levels of violence and insecurity, pervasive poverty and chronic malnutrition, and extreme vulnerability to the impacts of global climate change, as well as the impacts of these challenges on increased migration," according to Aid to Guatemala addresses "high levels of violence and insecurity, pervasive poverty and chronic malnutrition, and extreme vulnerability to the impacts of global climate change, as well as the impacts of these challenges on increased migration," according to the US government website that tracks foreign aid spending . Funding also focuses on agriculture, economic growth and food security.

El Salvador

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Aid from the US: $45.7 million

What it pays for: Aid to El Salvador pays for programs that provide greater educational and economic opportunities for "vulnerable youth in high-crime communities," Aid to El Salvador pays for programs that provide greater educational and economic opportunities for "vulnerable youth in high-crime communities," the US government says . "Assistance will also strengthen the capacity of El Salvador's security forces and law enforcement agencies to contribute to international and domestic security."

Mexico

President Trump deployed National Guard troops to the US-Mexico border when a caravan approached earlier this year. Now he's threatening to shut down the border entirely after a new caravan has formed.

haven't always been successful, the US has already shown its interest in pulling financial strings to influence Mexico's migration decisions. So far, when he's threatened to cut foreign aid as the caravan heads north, President Trump hasn't explicitly mentioned Mexico. But even though Trump's efforts to persuade Mexico to do things like pay for a border wall haven't always been successful, the US has already shown its interest in pulling financial strings to influence Mexico's migration decisions.

Aid from the US: $78.9 million