President Donald Trump announced Tuesday what he called a "blockade" of sanctioned oil tankers going into or out of Venezuela, ratcheting up American pressure on the regime of Venezuelan President Nicolas Maduro.

President Donald Trump demanded Wednesday that Venezuela return assets that it seized from U.S. oil companies years ago, justifying anew his announcement of a “blockade” against oil tankers traveling to or from the South American country that face American sanctions.

The presidents of Latin America's two largest countries urged restraint on Wednesday in the face of escalating actions from the United States toward regional neighbor Venezuela.

President Donald Trump ramped up pressure on Venezuela on Tuesday by announcing that he is ordering a blockade of all “sanctioned oil tankers ” entering and leaving the South American country.

As U.S.-Venezuela tensions rise, sociologist and historian Emmanuel Guerisoli wrote in Spanish in Venezuela’s El Nacional that a civil war is “very likely” if the United States tries to unilaterally oust President Nicolás Maduro. Newsweek has reached out to Guerisoli and the State Department for comment via email on Wednesday.

Mexican President Claudia Sheinbaum on Wednesday asked the United Nations to act to avoid bloodshed in Venezuela, while other countries expressed concerns about U.S. President Donald Trump's recent blockade announcement.

President Trump said the United States wanted to reclaim expropriated oil assets, setting off a nationalist reaction in a country where the resource holds a mythical status.