Disclaimer: although I know a bunch of former missileers, I am not, nor have ever been one myself.
The way I see it, anyway, a nation's ability to wage war of any sort depends on the willingness of the guys on the pointy end to wage it.
That would be as true in a silo, as on the front lines.
The difference, I think, would be the type of pressure one is under when the time comes. In the case of the guy in the silo, the supposition is that he can overcome the inherent revulsion of sending a missile off that will kill thousands or millions.
The military knows this, BTW, which is why they're pretty careful about who they'll allow to sit at the console. They want to make sure they've got people who, when given the launch order, will actually launch.