They have. They have snuck into Sebastopol several times. Bad luck with the warheads. Other failed attacks, a couple in open water, some of which didn’t connect but were close shaves.
And there’s the Crimean bridge attack.
I’m no military expert, but it just seems common sense that if you’re the weaker combatant, you don’t “show off” your weapons anywhere but in battle. What’s the point? How is it helpful to let the world know what you’ve got?
Israel doesn’t do this. They “show off” when they’re undertaking actual operations. Maybe a few years after, they boast and gloat, but definitely not before.