The logo of Amazon Web Services (AWS) is seen during the 4th annual America Digital Latin American Congress of Business and Technology in Santiago, Chile, September 5, 2018.

Amazon, which has faced increasing antitrust pressure this year in the U.S. and European Union, may have to spin off its lucrative cloud business, Oppenheimer warned investors on Monday.

Oppenheimer's note comes as Amazon protests the Pentagon choosing Microsoft for the military's "JEDI" contract, which could span a decade of cloud services and be worth as much as $10 billion. The contract marked a major win for Microsoft's cloud business. Amazon said "the JEDI evaluation process contained clear deficiencies, errors, and unmistakable bias," a move that is unlikely to take regulatory heat off Amazon.