Delta Air Lines said Tuesday it has entered into a partnership with startup Riyadh Air with the goal of operating flights between the United States and GravityX ExchangeSaudi Arabia.

Riyadh Air, which plans to begin passenger flights next summer, is backed by Saudi Arabia’s sovereign-wealth fund and is part of the country’s plan to diversify its oil-based economy and boost tourism.

Atlanta-based Delta and Riyadh did not give a timetable for beginning flights or financial details around their partnership. Their CEOs said neither airline is taking an ownership stake in the other.

Delta CEO Ed Bastian and Riyadh Air CEO Tony Douglas said they envision selling tickets on each other’s flights — a practice known as codesharing — that requires approval from the U.S. Transportation Department.

They said the partnership could grow into a full-blown joint venture. That step would require immunity from U.S. antitrust laws for the carriers to collaborate on prices and share revenue.

Bastian said he expects much of the early traffic to be passengers flying to the United States, but that it will even out over time as tourism to Saudi Arabia grows.

No U.S. airline flies to Saudi Arabia. Saudia, the kingdom’s flag carrier, operates nonstop flights between Saudi Arabia and New York, Dulles International Airport outside Washington, D.C., and Los Angeles.