Emergency Mobilization is the zeroth mission in Metal Slug: 1st Mission.
Unlike the later missions, the first mission pits the player on the game's three types of missions: on-foot, SV-000, and Slug Flyer. As such, destruction of the SV-000 and Slug Flyer leads to the next section of the mission rather than ending the mission outright. The player still has to complete a basic Prison Camp level and/or a Parachute Drop should the event occur. The mission ends with a fight with the Rebel VTOL.
Completing this mission proceeds to Mission 1 (Hurry On).