While such technologies exist, they matter very little if a country decides to preemptively strike us. With hypersonic missiles with nuclear warheads attached becoming a very real possibility, the only way to defend against them is the threat of total destruction for the country that fired them. Even so, there is no real guarantee that firing a nuke at a country would be enough to prevent a counterstrike at all. The idea of mutually ensured destruction basically means that countries with nukes can't fire at each other due to the threat of retaliation being able to wipe them out with us. This has effectively prevented the world's superpowers from going to war against each other but as a result, smaller scale wars have become far more frequent as a result of nuclear deterrence being so powerful of a threat that the worlds strongest countries are unable to directly fight or risk nuclear war as a possibility.
