WASHINGTON/MEXICO CITY (Reuters) - The U.S. Department of Justice (DOJ) said it is “deeply disappointed” by Mexico’s decision to close its investigation of ex-Defense Minister Salvador Cienfuegos, after the Mexican attorney general decided not to press charges. The decision, which Mexican President Andres Manuel Lopez Obrador publicly backed on Friday, and a document dump by Mexico’s government of U.S. evidence against Cienfuegos, threatens to strain strategic U.S.-Mexico security ties. On Friday, on Lopez Obrador’s instructions, the foreign ministry published a 751-page document showing the U.S. evidence, including detailed logs of alleged Blackberry communications. A DOJ spokesperson late on Friday called the decision to publicize information shared with Mexico in confidence deeply disappointing. “Publicizing such information violates the Treaty on Mutual Legal Assistance between Mexico and the United States, and calls into question whether the United States can continue to share information to support Mexico’s own criminal investigations,” the DOJ said. Mexico’s foreign ministry declined to comment on the DOJ’s statement. Analysts believe that other probes and court cases in which Mexico needs U.S. collaboration could be at risk. “Now they have created a major, major source of friction with the U.S., and that could really hobble not only this investigation but other investigations that President (Lopez Obrador) is really keen on,” said security analyst Alejandro Hope. Cienfuegos, who was minister from 2012 to 2018 during the government of former President Enrique Pena Nieto, was arrested in October at Los Angeles airport on charges he worked with a powerful drug cartel. U.S. prosecutors later dropped the case and returned him to Mexico to be prosecuted, with Lopez Obrador’s administration vowing a thorough investigation of the case. But on Thursday, less than two months after Cienfuegos’ return from the United States, Mexico’s attorney general office concluded that he had no contact with members of the criminal organization and said it will not pursue criminal charges. The DOJ spokesperson said the department “fully stands by its investigation and charges in this matter,” that the documents show the case against Cienfuegos was not fabricated, and the information was lawfully gathered in the United States through a proper U.S. court order, in full respect of Mexico’s sovereignty. “A U.S. federal grand jury analyzed that material and other evidence and concluded that criminal charges against Cienfuegos were supported by the evidence.” But some experts called into question whether the records of Blackberry communications released by Mexico, which were riddled with spelling errors, were actually written by Cienfuegos. “I will never defend Cienfuegos. The army committed all kinds of atrocities during the administration of Enrique Pena Nieto, but the DEA’s ‘evidence’ is frankly a joke,” John Ackerman, a constitutional law expert at the National Autonomous University of Mexico, said on Twitter. Ackerman suggested the Blackberry messages were “written by a third- or fourth-rate narco or soldier.” Security analyst Hope said the conversations are not a smoking gun against Cienfuegos, but also not completely exculpatory, adding that there is probably more evidence “out there that we don’t know of.”