then they're unsubstantiated
Ballistic missiles are visible to radar during their lift phase because the large rocket and it's exhaust plume. However, once the reach the top of their flight, the rocket is jettisoned and the re-entry vehicles are just free falling on a
ballistic trajectory. It's literally just a 6ft cone falling in from space, so putting stealth material over it isn't exactly far fetched. Even if it's not stealth, what are you going to do, shoot it down? It's multiple objects coming in at over 11,000mph spread apart by hundreds of miles and decoys can overwhelm any missile defense system for pennies on the dollar. Also the total flight time is like 30 minutes so an impractical level of vigilance and readiness is required.
The controversial
Strategic Defense Initiative was all about using orbital weapons to shoot down ICBMs during their vulnerable launch phase, precisely because there's not much you can do once it's on it's way down. Although interception and laser tech has improved significantly since the 80s:
https://en.wikipedia.org/wiki/Anti-satellite_weaponhttps://en.wikipedia.org/wiki/Iron_Domehttps://en.wikipedia.org/wiki/Tactical_High_Energy_LaserIn the "Metal Gear" series, what made the titular robot such an important weapon is that it could launch nuclear warheads from a rail gun, avoiding the detectable launch phase and allowing for stealth projectiles.
