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Molly Riley, Associated Press
Secretary of State Rex Tillerson is seen at the State Department in Washington, Wednesday, Feb. 22, 2017. President Donald Trump is sending his Tillerson and Homeland Security Secretary John Kelly to Mexico on a fence-mending mission made all the more challenging by the actual fence he wants to build on the southern border.

MEXICO CITY — President Donald Trump is sending his top diplomat and homeland security chief to Mexico on a fence-mending mission made all the more challenging by the actual fence he wants to build on the southern border.

U.S. Secretary of State Rex Tillerson and Homeland Security Secretary John Kelly will travel to America's southern neighbor as it anxiously rethinks its relationship with the world's largest economy.

Relations between the two countries have deteriorated sharply since Trump took office. Trump has insisted that Mexico pay for a border wall and has taken forceful steps on illegal immigration. He also has pledged to overhaul the U.S.-Mexican trade relationship.

Tillerson arrives late Wednesday in Mexico City. Kelly is traveling separately from Guatemala. They plan to meet with Mexican President Enrique Pena Nieto.