they are eminently detectable in the terminal phase, being sheathed in very hot plasma they are not easily detectable in the exo-atmospheric midcourse phase they are very easily detectable during the boost phase, as long as there is a satellite or other asset with a multispectral light sensor watching the horizon in the right direction, which is not a given they are avoidable, in the sense that they take minutes or tens of minutes to reach their targets, while a competent c4isr setup can generate an alert/move order in a couple minutes. you are not going to sink carriers underway with these things or stop an advancing tank column outside of some very contrived scenarios.  but, buildings can't dodge, planes are rarely kept at alert 5 for more than a few hours at a time and large concentrations of troops are notoriously sluggish.
National Bolshevik