This speech is going to scare the hell out of some of our most enthusiastic allies.

The NATO countries (Estonia, Latvia, Lithuania) that border Russia all have border cities and border regions with large ethnic Russian populations.

Under Putin, Russia has already occupied or annexed the equivalent regions in its non-NATO neighbors and near neighbors (Moldova, Ukraine, Georgia).
It did so because Putin assumed (correctly) that our current President would respond by looking at both sides of both sides before deciding to do nothing.

Russia has, however, left its NATO neighbors alone.
Why? because Putin knows that if he touches them, NATO will act and act fast.  
Estonia, Latvia and Lithuania are (with good reason) genuinely enthusiastic about NATO and do everything they can to support NATO, its forces and its mission.

If, because of this speech, Putin decides we are going to abandon them the way we have abandoned the others, Mr Trump may have just started Russia's next war.