To start Field Op #40, Open up your Spy Phone and travel to the HQ. Once you are there, walk up to the big monitor on the upper right side of the HQ, It says, "Field Ops".
Once you have done that, A message will pop up from Gary. This is what the message will look like:
To start the Field Op, go to the Iceberg. Once you are in the Iceberg go to the left side.
After you have done this, your Spy Phone will ring. Answer your Spy Phone. You're going to have to complete the puzzle.
Once you have successfully done this, you have complete your 40th Field Op and will receive a Medal. You can save it for some gear in the future, each medal adds up! Congratulations Agent, Well done!