Also, the first sentence of the EO references the law of war.
Section 1. Findings. (a) Consistent with long-standing law of war principles and applicable law, the United States may detain certain persons captured in connection with an armed conflict for the duration of the conflict.
Also, the first sentence of the EO references the law of war.
This is pretty direct confirmation.
Perhaps anticipating some planned FF AntiFed/MagaGlowie riots?