Screen Snip of the etymyonline entry for "belligerence" stating: belligerence(n.) "warlike nature or actions," 1804; see belligerent + -ence. Related: belligerency. Middle English had belligeration "warfare." Related entries & more belligerent(adj.) 1570s, "waging war, engaged in hostilities," from Latin belligerantem (nominative belligerans), past participle of belligerare "to wage war," from bellum "war" (see bellicose) + gerere "to bear, to carry" (see gest). The noun meaning "party or nation at war" is from 1811. Related: Belligerently.
because of course the most belligerent president in U.S. history is going to engage in war when his polls plummet and more scandals are to come.