The killing of Qasem Soleimani was “most likely unlawful,” UN Rapporteur on extra-judicial executions Agnès Callamard tweeted.

She said the targeted killings “violate international human rights law,” adding that “outside the context of active hostilities, the use of drones or other means for targeted killing is almost never likely to be legal.”

She further argued that “drone killing of anyone other than the target (family members or others in the vicinity, for example) would be an arbitrary deprivation of life under human rights law and could result in State responsibility and individual criminal liability.”

At least six people were killed alongside Soleimani in the drone strike. The UN Rapporteur said the killing of other individuals alongside Soleimani was “absolutely” unlawful.

Callamard wrote that, while under customary international law states may take military action in case of imminent attack, the Pentagon’s statement mentions that it aimed at “deterring future Iranian attack plans.”

"Future is not the same as imminent which is the time based test required under international law.” She added that “the test for so-called anticipatory self-defence is very narrow.”