Three years ago, the Kyaw Thaung family partied at the Pegu Club. The venerable Burmese-Irish clan had restored the teak-lined establishment to its 19th-century glory, evoking the days when gin-sipping colonialists ruled. The Pegu Club project befitted the family’s East-meets-West positioning and the optimism of a country newly engaging with the world.

Amid periodic power cuts in the rest of Yangon, the Kyaw Thaungs danced and sipped champagne among the new elite, including young entrepreneurs returned from exile, bejeweled daughters of generals, and even former political prisoners suddenly responsible for attracting foreign investment to the latest frontier market.

As Myanmar’s military dictators ended decades of isolationism, the Kyaw Thaungs seemed to embody the perfect mix: an august family with a long history of charitable giving that was committed to the kind of business reforms needed to coax a corrupt, closed country into the global economy. But the main source of the family fortune, purported vaguely to be from property and import-export companies, was concealed behind a facade.

For all their efforts to differentiate themselves from the drug lords and business cronies who dominated Myanmar’s economy, the Kyaw Thaungs were quietly equipping one of the world’s most brutal militaries. Their partnership with the Tatmadaw, as the Myanmar military is known, deepened even as its generals committed ethnic cleansing against Rohingya Muslims. And it continued into this year, when the army staged a coup and seized full power of the country, killing more than 1,300 civilians so far, in the estimate of a monitoring group.