Fighter aircraft typically have jet engines buried inside the fuselage to enhance speed, maneuverability, and reduce radar visibility. This design allows for a smaller profile, which is crucial for evading threats. Additionally, placing engines within the fuselage minimizes air resistance and keeps the moment of inertia low, improving agility during combat. In contrast, commercial aircraft place engines on the wings to maximize fuselage space for cargo. Overall, the internal engine placement is a strategic choice that supports the operational needs of fighter jets.