Coriolis's inertial force is a movement perceived only by observers who are in a non-inertial frame of motion (for example, planet Earth). Newton's laws of motion are valid for inertial reference systems, ie without acceleration. To use them in a non-inertial system, one can adapt them by introducing fictitious forces. Therefore, it is common to call the Coriolis effect as a fictitious or inertial force, since it is only an acceleration (unit of measure is m/s² and not newtons).
