Enter these cheats at the position they should happen:

Air Strike    :  A, B, C, left, down, right, up, left, down,
                 right, up, C
Ionen Canon   :  A, B, C, left, down, right, up, left, down,
                 right, up, B
Nuclear Strike:  A, B, C, left, down, right, up, left, down,
                 right, up, A