There should be a random chance you set one of the missiles off that you're defusing. So for example:

country B defuses country A.
At random one of the missiles country b was defusing goes off and damages country A.

It makes since to me that when someone is attempting to defuse something explosive there should be the risk of setting it off.

The down side to that would be that if he sets off a bomb only one missile is defused that turn.

How about if a missile explodes, you lose a portion of your spies?

Yeah that would be also a good negative to it also. You'd lose as many spies as you would for a failed op, only disable one missile that turn, however it blows up in your targets country causing damage.

hm that's an interesting idea... kill spies and set off a missile... you could do it on purpose

Well I wouldn't make it a new spy op but rather a % chance that could happen while defusing. If you had a new spy op for it you'd want to make the spies killed a lot more than if it was just a failed op because that would be over powered otherwise.

I agree to this change. Of all the spy ops, defuse missile is the most damaging, especially when one clan entirely disarms another clan of all missiles which requires few turns relative to the damage done.