I think that weapons range, combined with either precision targeting or large numbers, gets that job done. Picture a world without nukes, but with lots of highly accurate ICBMs and SLBMs. The attacker can expect to be attacked, with the destruction being stuff like the Kremlin or Whitehouse or parliament building.

In the days of WWII, an attacker could rightly feel confident that there could not be an immediate response that strikes anything of importance. The attacker might even believe that such a response could not be possible ever in the future. Poland could be invaded without any realistic worry that Berlin would be attacked that same day, and a bit of optimism turns that into Berlin being safe.