Delta Air Lines and Riyadh Air signed a strategic cooperation agreement in July 2024 (read more here), and as part of that deal, Delta was expected to begin service to Riyadh in late this year.

Delta announced last month that it will begin Atlanta–Riyadh service in October 2026 (read more here), and it has now confirmed the start date (October 23rd) and that the flights should be available for sale as of today (per Delta’s comms team).
A great solo travel tip spotted this week on LoyaltyLobby.