[alwa]

Aren’t these export controls rather than import controls? That is, if a company in their bloc does succeed at developing cryptographically-relevant quantum computers, they’d just as soon that company not sell that tech on to the adversary?

As you said, they’ve loudly assumed it’s possible—so wouldn’t it make sense for them to draw a line in the sand now, before the horse has bolted, to indicate where the “now it’s a national security matter” threshold lies?