Whereupon they will create large numbers of new projectiles to create problems for any spacecraft launched or stationed in that orbit. Looks like going forward, any new launches will have to factor in the weight from additional armor plating.
If they can just slow it all down enough, the orbits will decay and the debris will all burn up in the atmosphere.
I had the idea of throwing a giant foam ball into LEO to slow things down, but I’m sure a lot of holes can be poked in that.