The Mo So massacre occurred during a period of intense conflict in Myanmar, following the February 2021 military coup. The Tatmadaw, Myanmar's military, had seized power, leading to widespread protests and civil disobedience movements across the country. In response to the protests, the military increased its operations in various regions, including the conflict-prone Kayah State, where Mo So is located. On December 24, military forces attacked a gathering of civilians in the area, resulting in the deaths of at least 44 individuals, marking this as one of the more lethal attacks against civilians in a series of assaults documented since the coup.

The massacre was particularly shocking due to the nature of the attack; it targeted civilians who were attending a local event, which underscored the extreme measures the military was willing to take to suppress dissent. Witnesses reported airstrikes and the use of heavy artillery against populated areas, further exacerbating fears among the local populace. This incident not only represented a blatant violation of human rights but also illustrated the growing hostility between Myanmar's military and the civilians seeking democracy and autonomy.

Local and international responses were swift, with human rights organizations condemning the violence and calling for accountability. The attack at Mo So amplified the urgency for international intervention and raised concerns about humanitarian conditions in Myanmar as conflict displaced thousands of people. The massacre became emblematic of the brutal tactics employed by the military in its attempts to maintain control over the nation as a whole, exacerbating an ongoing crisis that continues to unfold in the region.