When U.S. President Barack Obama hosts a meeting of Southeast Asian leaders in California this week, his Myanmar counterpart Thein Sein will be notably absent.

Myanmar's outgoing president abruptly pulled out of the summit as secretive talks continued between his country's powerful military and the incoming government of Nobel laureate Aung San Suu Kyi.

For his admirers, a smooth transition of power would seal Thein Sein's legacy as the former general who led Myanmar's dramatic emergence from nearly half a century of military dictatorship.