For what purpose did Trump weaken U.S. deterrence?

So what if, in his speech last week to NATO, Donald Trump didn’t explicitly reaffirm the provision that an attack on one is an attack on all?
What’s the big deal? Didn’t he affirm a general commitment to NATO during his visit? Hadn’t he earlier sent his vice president and secretaries of State and Defense to pledge allegiance to Article 5?
And anyway, who believes that the United States would really go to war with Russia — and risk nuclear annihilation — over E