The term “counter-terrorism” is linguistically revealing.
Terrorism is a grave crime, and as such, law enforcement needs to investigate, charge, and prosecute individuals who commit it. That is the response of a society which respects the rule of law.
Responding to terrorism by committing terrorism, which is what counter-terrorism would linguistically mean, and which is often in fact the strategy of state authorities; is also a grave crime.
What the military is doing in Rakhine, ostensibly in response to militant activities by armed groups whom they classify as terrorists, is precisely this: responding to terrorism with terrorism.
If ARSA, or any other group, has in fact committed terrorist acts, the appropriate response is to identify culprits, arrest, charge, and put them on trial.
Responding to what the state deems to be terrorist activity by indiscriminately firing upon civilians, letting loose paramilitary extremists, burning the homes and whole villages of innocent people, constitutes collective punishment of an entire population in retaliation for the crimes of certain individuals; and this is a war crime.
I do not see that the ASEAN charter which upholds the principle of non-interference can override the duty of states to enforce international law; rather, the burden of responsibility among ASEAN members to ensure that all signatories to the charter comply with international law, should be greater precisely because they have formed a brotherhood of nations.