This is the 17428th most frequent Russian word.
терроризму
The Russian word "терроризму" means "to terrorism" (dative case of "терроризм," which means "terrorism").
The word "терроризмом" in this sentence is instrumental case, indicating the means by which the subject undertakes an action.
Борьба с терроризмом требует международного сотрудничества.
The fight against terrorism requires international cooperation.
The word "терроризму" here is in dative case, indicating the entity that is the recipient or indirect object of the action described.
Терроризму необходимо противостоять всеми законными методами.
Terrorism must be countered by all legal means.
The word "терроризму" is in dative case, showing that the action, 'posed by', is directed towards terrorism.