Putin is upset because an anti-missile shield unbalances the nuclear standoff. Nuclear security at this juncture rests on mutually-assured destruction -- you hurt us, and we'll hurt you just as bad, if not worse. If we can stop their missiles and they can't stop ours, this creates an imbalance that might motivate someone -- particularly them -- to strike unexpectedly and unilaterally. If they felt we were acting aggressively, they might conclude that they had no choice but to attack first, before we were prepared.

A scary scenario.

j