The rules that use the category "<enemy_vehicles>" are:

<follow_unit_command-not_with_compass_direction>

<follow_unit_verb> <enemy_vehicles>

<follow_unit_command>

<follow_unit_verb> <enemy_vehicles>

<pursue_command>

<pursue_verb> <enemy_vehicles>

<pursue_command-not_with_compass_direction>

<pursue_verb> <enemy_vehicles>