U.S. Secretary of State Mike Pompeo, right, greets a young Venezuelan migrant at a migrant shelter, as he's given a tour by Colombian Vice President Marta Lucia Ramirez, behind, and Colombian President Ivan Duque, not in picture, in La Parada near Cucuta, Colombia, on the border with Venezuela, Sunday, April 14, 2019. Pompeo is on a four-day Latin American tour, making his final stop at the Colombian border to meet with representatives of Venezuelan refugees. (AP Photo/Fernando Vergara)

Venezuelan migrants yell "We want freedom!, and "Intervention!" toward U.S. Secretary of State Mike Pompeo as he walks on the Simon Bolivar International Bridge in La Parada near Cucuta, Colombia, on the border with Venezuela, Sunday, April 14, 2019. Pompeo is on a four-day Latin American tour, making his final stop at the Colombian border to meet with representatives of Venezuelan refugees. (AP Photo/Fernando Vergara)

U.S. Secretary of State Mike Pompeo is visiting with Venezuelan migrants in Colombia as he wraps up a four-nation tour of South America aimed at pressuring Venezuela's socialist leader, Nicolas Maduro.

Pompeo arrived Sunday at a migrant center in the border town of Cucuta with Colombia President Ivan Duque. Not far away Venezuelan security forces sat on high alert at the Simon Bolivar international bridge separating the two countries.

The migrant center has been the first stop for some of the more than 3 million Venezuelans who have fled hyperinflation and political upheaval in their homeland.

The U.S. was the first of more than 50 nations that in January recognized opposition leader Juan Guaidó as Venezuela's interim president. But significant popular support for Guaidó hasn't loosened Maduro's grip on power.