The US Justice Department filed a lawsuit Tuesday to block the alliance between American Airlines and JetBlue that it says will harm travelers by reducing competition. “In an industry where just four airlines control more than 80 percent of domestic air travel, American Airlines’ ‘alliance’ with JetBlue is, in fact, an unprecedented maneuver to further consolidate the industry,” Attorney General Merrick B. Garland said in a statement. Attorneys general in six states and the District of Columbia joined the lawsuit over the airlines’ Northeast Alliance, which was announced in July 2020.