This is the 1600th most frequent Russian word.
террористической
"Of or relating to terrorist."
The usage of "террористической" here is to describe the nature of the act being terroristic.
Этот инцидент был расследован как террористической акт.
This incident was investigated as a terrorist act.
Here, "террористической" is used as an adjective to qualify the noun "угрозой" (threat) that pertains to terrorism.
В фильме был изображен герой, сражающийся с террористической угрозой.
In the movie, a hero fighting against a terrorist threat was depicted.
The term "террористической" describes the type of activity here, specifically associated with terrorism.