China Southern Airlines has decided to leave the SkyTeam alliance effective January 2019, leaving China Eastern and Xiamen Air as the two remaining members from mainland China.

The decision opens the possibility of China Southern joining the Oneworld group, a founding member of which—American Airlines—bought a $200 million stake in the Guangzhou-based carrier in 2017. The two airlines have since signed a code-share agreement, further generating speculation for more than a year of China Southern’s possible move to Oneworld.

China Southern said its decision reflects its strategic development, the changing trends of the global aviation industry, and the evolution of alliances.

SkyTeam said in a statement that it and China Southern have agreed to work closely together “to ensure a seamless transition for all customers and partners.” The process will run throughout 2019 and wrap up by the end of that year, it concluded.