Is that peace? If so, Trump has a case. But I don’t think it’s peace.
For one thing, while it’s true that Trump did not start a war with Iran, he did take a high-risk gamble in assassinating terrorist mastermind General Qassem Soleimani, and the fact that the gamble has so far paid off doesn’t invalidate how risky it was at the time, nor the fact that, in that instance, he did listen to his extremely hawkish advisors. Moreover, Trump pulled out of the nuclear deal that was one of Obama’s notable accomplishments, which has, predictably, led Iran to move further toward nuclear potential while shredding any American diplomatic leverage. While Trump has not started any new wars, one of his first acts was to dramatically escalate America’s involvement in Saudi Arabia’s near-genocidal war in Yemen, a war so unpopular that he had to veto a bi-partisan war-powers resolution to keep fighting. Meanwhile, from North Korea to China to Venezuela, Trump has been as promiscuous with his threats as he has been with his praise of foreign dictators. If he has rarely backed those threats up with military action, that is not a sign of a dove but of a paper tiger.
As for diplomacy, while Trump has claimed to want better relations with Russia, it’s hard to discern any actual improvement there. Instead, America has torn up arms agreements with Russia in the hopes of adding China to them, a gambit which failed, leaving the future of New Start in serious question. The same can be said about North Korea, where Trump’s bold diplomatic opening has led nowhere. Chalk these failures up to conflict between Trump and his subordinates, or to Russian and North Korean determination to pursue their own interests, or what have you — regardless, a stated eagerness for better relations is not the same thing as achieving them, and the achievement is what’s lacking.