No. The Soviets were pretty much oriented towards "Launch on Warning" in the 80's so the US made sure to notify them for tests. And then only fired from places like Vandenberg on the coast of California. Any launch from a silo out in the middle of Kansas would be a war launch (or a really really unfortunate accident.)

There have also been test firings from missile subs. But again, lots of notification, and done from a latitude/longitude that made it obvious it was a test.

Twice a year an active ICBM is picked at random from the mid-west, the nuclear warhead is removed, and the rocket is taken to VAFB where it is launched at Kwaj. The entire purpose of this very common event is to make sure that ICBM's work as expected. I live in the area and am woken up by these tests. If you live on the West Coast, you can see them. You can also Youtube them (VAFB missle test).

I am not sure that you mean by "actual combat conditions", but Russia quite regularly tests its ICBMs by launching them to the Kura test range [0] in Kamchatka. Tests usually have distance of 5-6 thousand kilometers and often include tests of MIRVs [1] with mass-equivalents of nuclear warheads.

[0]: https://en.wikipedia.org/wiki/Kura_Missile_Test_Range

[1]: https://en.wikipedia.org/wiki/Multiple_independently_targeta...

If you take Command and Control[0] to be an authoritative source, then no I don't believe so. We've come close to accidentally launching on both sides but no combat deployment has occurred, if it did it would likely be the end of our current civilization.

[0] https://www.amazon.com/Command-Control-Damascus-Accident-Ill...

Yes-ish. IRBM not an ICBM: https://foxtrotalpha.jalopnik.com/the-only-full-scale-test-o...

nope