Myanmar's onetime opposition party successfully chose its first civilian president this week to replace President Thein Sein, a former general. The accession of National League for Democracy (NLD) stalwart Htin Kyaw to the office March 30 will end the slow and planned transition from military to quasi-civilian rule, a process that began in 2010. The NLD has never held power and, perhaps because of its decades in opposition, enjoys high levels of popularity and a party brand that emphasizes sound, Western-style economic reform. However, its attempts to govern the restive border regions through political means will be sabotaged by the military....