From The New York Times:
The Pentagon used a secret aircraft painted to look like a civilian plane in its first attack on a boat that the Trump administration said was smuggling drugs, killing 11 people last September, according to officials briefed on the matter. The aircraft also carried its munitions inside the fuselage, rather than visibly under its wings, they said.
And:
Retired Maj. Gen. Steven J. Lepper, a former deputy judge advocate general for the United States Air Force, said that if the aircraft had been painted in a way that disguised its military nature and got close enough for the people on the boat to see it — tricking them into failing to realize they should take evasive action or surrender to survive — that was a war crime under armed-conflict standards.
“Shielding your identity is an element of perfidy,” he said. “If the aircraft flying above is not identifiable as a combatant aircraft, it should not be engaged in combatant activity.”
Article 37 - Prohibition of perfidy1. It is prohibited to kill, injure or capture an adversary by resort to perfidy. Acts inviting the confidence of an adversary to lead him to believe that he is entitled to, or is obliged to accord, protection under the rules of international law applicable in armed conflict, with intent to betray that confidence, shall constitute perfidy. The following acts are examples of perfidy:(c) the feigning of civilian, non-combatant status
From the DOD Law of War Manual:
5.22.2 Perfidy - “Kill or Wound”. It is prohibited to use perfidy to kill or wound the enemy.
And the US Navy/Marines/Coast Guard Handbook on Naval Operations:
Honor prohibits perfidy, the misuse of certain signs, fighting in the enemy’s uniform, feigning nonhostile relations in order to seek a military advantage...
And so on.
Perfidy. Prohibited. War crime.
