The army's seizure of power halted the Southeast Asian nation's move toward democracy that began when Suu Kyi's party took office in 2016 for its first term, after more than five decades of military rule.
The military says it acted because November's election, which Suu Kyi's National League for Democracy won in a landslide, were marred by irregularities.
The protesters are demanding that power be restored to the deposed civilian government and seek freedom for the nation's elected leader Aung San Suu Kyi.
