A Mexican national is accused of working on behalf of Russia while trying to conduct surveillance of a U.S. government source in Miami, the Justice Department announced Tuesday.Hector Alejandro Cabrera Fuentes, a Mexican national, has been arrested and charged with a single count of failing to register as an agent of a foreign power, Russia.A senior Justice Department official said that for now, authorities aren't too concerned about the surveillance effort Fuentes is believed to have carried out. He has not been charged with espionage.The complaint alleges that Fuentes was recruited last year and that at that time he was directed by a Russian government official to rent an apartment in Miami-Dade County not in his own name and without telling his family about their meetings. Fuentes is alleged to have then traveled to Russia and discussed the arrangements.Fuentes is alleged to have traveled to Moscow again this month to meet with the Russian government official. According to a Justice Department statement, "the Russian government official provided Fuentes with a physical description of a U.S. Government source's vehicle and told Fuentes to locate the car, obtain the source's vehicle license plate number, and note the physical location of the source's vehicle."Fuentes was then tasked with reporting to the Russian official again in April or May of this year to inform him of the results of his search for the vehicle, according to the statement.Fuentes is alleged to have entered the location where the U.S. government source resided last Thursday by tailgating another car to get through the gate. Security stopped Fuentes, who did not provide a correct name for whom he was visiting, and in the meantime, his wife took photos of the U.S. government source's license plate, according to the statement.Fuentes was stopped Sunday at Miami International Airport en route to Mexico City. The documents say that the license plate photo was found on Fuentes' phone through WhatsApp and that Fuentes admitted to law enforcement officers that he was directed by the Russian government official to conduct the operation.His first court appearance is scheduled for Friday morning, and his arraignment is set for March 3.