I'm saying nationalism, like socialism, utters sweet sounding rhetoric that when put into practice causes economic decline and chaos in international relations, not to mention internal strife among citizens of the country practicing it. Donald Trump has embraced the rhetoric (probably believes it) and has uttered those sweet sounds to naïve people who have joined his team and will follow him over the cliff's edge. Remember: he thinks he could shoot someone on the street and his adoring followers would cheer him. Nationalism leads to destruction very similar to socialism.
Or, he’s trolling.