"We will be forced to close the southern border entirely if the oDemocrats do not give us the money to finish the Wall & also change the ridiculous immigration laws that our country is saddled with," Trump posted on Twitter amid the government's partial shutdown.
According to Trump, the U.S. government "loses soooo much money on trade with Mexico under NAFTA, over 75 Billion Dollars a year."
Mexican President Andres Manuel Lopez Obrador (AMLO) said his government would act with "prudence," avoiding provocations.
"We are always going to defend our sovereignty, in the case of migrants, we have already shown our respect for the right of human beings to seek life, to emigrate, we always protect migrants, defend their human rights."
Trump has threatened to cut off all economic aid to Honduras, Guatemala and El Salvador, accusing the Central American nations of doing nothing to prevent migrant caravans from advancing to the United States.
"Honduras, Guatemala and El Salvador are doing nothing for the United States but taking our money," Trump said.
"Word is that a new caravan is forming in Honduras and they are doing nothing about it. We will be cutting off all aid to these 3 countries - taking advantage of U.S. for years!"