New Delhi, Dec. 20 -- A number of Mexican train crews who had just hauled trains over the border to American rail yards in Texas had trouble understanding important safety information in English during recent focused inspections the Trump administration ordered.

Railroads Union Pacific and CPKC routinely rely on foreign crews at times to bring trains over the border to their rail yards in the U.S. before switching to American engineers and conductors. The Brotherhood of Locomotive Engineers and Trainmen union said handoffs used to happen right at the border. The engineers union has been worried about using foreign crews for some time because of safety, security and job concerns.

The Federal Railroad Administration sent letters to both r...