The word "de-escalation" essentially means to reduce something or bring it down a notch. Antonyms for this word would be "escalation" or "intensification," which indicate an increase in something, whether it is a conflict, tension or any other kind of problem. Another antonym could be "aggravation," meaning to make a situation worse instead of making it better. "Deterioration," "worsening," or "exacerbation" could also serve as antonyms for "de-escalation." Ultimately, when trying to convey the opposite of "de-escalation," it is important to use a word that denotes an increase in intensity or severity rather than a decrease.