What are Delta Airlines inter airline agreements?

The main agreements are with Air-France-KLM-Alitalia. There are other SkyTeam partners too. These are Aeroflot, Czech Airlines, Korean Air, AeroMexico, Alitalia, Tarom, Air Europa, China Southern, Kenya Airways, Aerolineas Argentinas, Vietnam Airlines.

They have a strong agreement with Alaska Airlines (but not part of Skyteam) though as of Dec 2013 this relationship is under strain due to Delta expanding in Seattle the main hub of Alaska.

In addition to SkyTeam partners, Delta Air Lines also has codeshare agreements with the following airlines as of April 2011. Air Nigeria, American Eagle, Avianca, China Airlines , Garuda Indonesia, Gol Transportes Aéreos

Hawaiian Airlines, Horizon Air, Olympic Air, Royal Air Maroc, V Australia