The repercussions of the controversial visit by Cambodian prime minister Hun Sen to Myanmar have exposed fault lines in Asean’s response to the brutal military coup in the latter nation.

It is notable that while Myanmar’s democratic reversal following the bloody coup, is one of the most dramatic examples, many Asean nations have experienced democratic backsliding and most of the region’s population live under single-party dictatorships, military governments or compromised democracies.

Former Thai foreign minister Kasit Piromya, speaking in his capacity as...