Trump has genuinely increased the economic pressure on North Korea through United Nations sanctions, and the pinch may increase. But one of the worst mistakes in international relations, plaguing us from Vietnam to Iraq, is to operate on wishful thinking rather than reality, and I fear that’s what’s happening here in a perilous way. To be blunt, Trump’s strategy frightens me. In speech and through Twitter, he is escalating a conflict and trumpeting military options as he insists on a goal of denuclearization that is unachievable, a tactic of Chinese pressure that is unrealistic and a premise of regime fragility that is wishful thinking. That’s how wars happen.