To make the missions extra hard and to start with some medals type in INVALIDCODE you will the be taken to the level where you destroy the train. As normal finish the campain to choose the other missions.

(0=zero, o=letter o)
(1=one, I=letter I)

South America
Level 1-oNHV0V6VEBDU55Q
Level 2-2NH70V9VEFDQ592
Level 3-7RH30V7AEFD64BI
Level 4-8NH30V8EEJD24PI

Gulf 2-Oil Dispute
Level 1-VNHR0V0E6JDE53I
Level 2-0RHV0Uo66NDA53A
Level 3-IFHD0UoU6RDM5P2
Level 4-NJHP0UKE6VDI5BI

Stealth
Level 1-o7HP0UoQAUDE45A
Level 2-U7HL0UNIAUDA5RA
Level 3-AFHP0UKUA2DM4HI

Central America
Level 1-FJHL0UGII2CE4KI
Level 2-G7HH0U72I2CA5R2
Level 3-2BHP0URQI6CM58A

South China Sea
Level 1-KRG50URQ26GE4J2
Level 2-0RGL0UTI3AGA5UI
Level 3-FRG9S1CM3EGM52I

Panama
Level 1-93G5SD9UNGGE4oA
Level 2-VVG5SHUENGGA4SQ
Level 3-JNGH4CPUNKGM5TI

Eastern Europe
Level 1-L3GG4406VoEE5R1
Level 2-F7GK5S2QV0EA41A
Level 3-27GK50UMV4EM58Q

Gulf 1-Canyon
Level 1-7FGK48T6R8ME4NI
Level 2-8JGK48VUR8MA5JQ
End-T7GK28U2SCMM4oI