This is the 8869th most frequent Japanese word.
標的
Target; objective; mark.
In this sentence, "標的" means "target," specifically referring to an object or entity aimed at during a hunt.
狩人は鹿を標的に狙いを定めた。
The hunter aimed at the deer as the target.
Here, "標的" signifies the target for an action, often negative like an attack, contextualizing the system as something that might be aimed at.
セキュリティシステムは攻撃の標的にならないように設計されている。
The security system is designed not to become a target of attacks.
In this context, "標的" is figuratively used to denote an objective or goal pursued in a project.