The US wants Europe to carry more of the alliance's rapid-response burden. The problem is that the missing pieces are the hardest ones to replace. And the transition phase opens opportunities for Putin.

Still, Europe is waking up and starting to slowly march in step.

The US reduction could be the shock that turns the European direction of travel into an irreversible structural shift. Or it could create a gap that Russia exploits before Europe fills it.

In my crystal ball, both outcomes are genuinely possible. Which one arrives first is the question that will define the next ten years of European security.

Read my take here: