Trump managed not to insult South Korean President Moon Jae-in or the Korean people. More importantly, he did not directly threaten nuclear war with North Korea or threaten to withdraw US forces from the Korean Peninsula.
He reaffirmed the US-South Korean alliance, albeit without the standard "ironclad" language, and he said, "I know that the Republic of Korea, which has become a tremendously successful nation, will be a faithful ally of the United States very long into the future," without saying that the reverse would also be true. So, measured by the admittedly low standard of not saying something that might trigger war and risk millions of lives, the speech was one of Trump's best.
The bad news is that Trump did not articulate a new strategy for dealing with North Korea. He articulated a willingness to talk to North Korea, which is good, but he continued his insistence on denuclearization as a precondition for talks -- "We are only prepared to discuss this brighter path for North Korea if its leaders cease their threats and dismantle their nuclear program" -- which is not so much bad as it is pointless. North Korea will never denuclearize, and insisting on denuclearization as a precondition to talks is tantamount to saying there will be no talks.
Trump's choice of words was not especially bombastic or aggressive in their tone, but saying, "We will not allow American cities to be threatened with destruction," is an extreme and dangerous statement in its substance -- if Trump means what he says.
North Korea is indeed a threat -- to South Korea, Japan, the United States and even to global stability -- but so was the Soviet Union. The Soviets were far more aggressive than the North Koreans, and yet we avoided direct military conflict for decades. We should not be afraid of threats from North Korea, but we should be concerned with their actions.
Trump was wrong when he said to Kim Jong Un directly, "The weapons you are acquiring are not making you safer." They are in fact doing exactly that.
Kim knows that nuclear weapons are the only thing guaranteeing his survival, but that using them will guarantee his destruction. A single Trident II missile, launched from an Ohio-class submarine, carries eight warheads, each with up to a 455-kiloton yield -- and an Ohio-class submarine can carry 24 Trident II missiles. One missile could turn Pyongyang into a smoldering pile of ash. Kim knows this as well as we do.
Kim will not talk about denuclearization, and he is unlikely to approve any agreements with the United States until he has achieved a limited second-strike capability -- the ability to destroy an American city even after we have launched an attack against him. But after that there will be plenty to talk about.
We held many arms control talks with the Soviet Union and reached many agreements (including limiting the number of warheads on the Trident II to eight). There is no reason not to pursue similar such talks, which we can do without formally accepting North Korea as a nuclear power.
Trump's speech avoided the bombastic, hyper-aggressive tone of his past statements on North Korea, and for that I suppose we should be grateful, but it would be nice if the bar for a good speech were higher than it not producing casualties.