^Almost. Se is a pronoun, not a verb. It generally means himself, herself, oneself, itself, or themselves.
Understanding French Pronominal Verbs
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Sometimes a French pronominal verb doesn’t literally mean “oneself”. Sometimes it is used where a passive voice construction would be used in English (Spanish reflexive verbs are used this way too). Sometimes it has an idiomatic meaning.
In the case of the Trump example, my guess it that the se expresses a nuance. Il s’attaque and il attaque can both be translated as he attacks, but il s’attaque could also be translated as he tackles, according to Google Translate. So it conveys a more vivid mental image. Picture Trump hurling himself bodily at a gaggle of reporters.
Reflexive constructions are weird in that expressions that are reflexive in some languages might not be reflexive in others.