The revision that best adds a subjective tone is:
Whereas the successful prosecution of the war requires necessary protection against dangerous Japanese spies and against their sabotage to vulnerable national-defense material, national-defense premises, and national-defense utilities. . . .
This version introduces language that conveys a sense of urgency and alarm, emphasizing the perceived threat from a specific group (Japanese spies) and describing the national-defense assets as "vulnerable." This choice of words adds an emotional weight and a more subjective perspective to the original excerpt.