The proposed merger of United Airlines and Continental Airlines cleared its first regulatory hurdle on Tuesday, as the European Union said it would approve the deal. But the merger, which would create the largest airline in the world, must still pass muster with U.S. antitrust officials. The mega-deal is expected to face far more rigorous scrutiny from the U.S. Department of Justice, which isn’t expected to wrap up its probe until later this year.

European officials, in a review of the transaction that began on June 21, quickly determined that it wouldn’t adversely affect competition, given the relatively light overlap between United and Continental on trans-Atlantic routes.

However, the EU continues to separately investigate a proposed joint venture that would allow United, Continental, Air Canada and Germany’s Lufthansa AG to closely coordinate north Atlantic flights, as well as share revenues.