Aaron MacLean in the WSJ with an op-ed reminding us what an armed Europe looked like in the 20th century. (And while he focuses on the 20th century the arguments would hole true for most of the previous 20 centuries)

He asks:

Do we want European states to rearm, to achieve something closer to strategic self-sufficiency, perhaps including nuclear proliferation to the east?

And reminds us:

Perhaps we forget the vast slaughterhouse into which the Continent transformed on two occasions in the first half of the last century

He concludes:

In the short run, the main risk is still that European nations will overfund their social priorities, underfund their security, and fail to deter further westward Russian expansion…

There is… a risk for a disengaged America even if Europe does rearm. Putting these countries on their own feet may merely be the prelude to their hands reaching for one another’s throats. The two possibilities aren’t mutually exclusive…