The tweet in question:
Just landed - a long trip, but everybody can now feel much safer than the day I took office. There is no longer a Nuclear Threat from North Korea. Meeting with Kim Jong Un was an interesting and very positive experience. North Korea has great potential for the future!
Right now, I don't believe that North Korea has the ability to strike American cities with nuclear missiles. My understanding is that North Korea has nuclear devices but hasn't perfected the long-range missile to hit and hasn't miniaturized and hardened the warheads enough to survive the trip and explode. As I heard one expert say (or read it, I forget)--if he's right--North Korea would have to emplace a nuclear device on their side of the border to detonate it and damage anything in the south; or put it in a ship and sail it somewhere.
So if the question is whether North Korea's threat to strike has ended, that threat actually isn't here yet--that's why I've figured we're on a deadline of North Korea taking real steps to reverse course before we have to strike to stop North Korea's nuclear program before they can hit us.* So on that measure, the complaint about the tweet is wrong.
So the question is on whether the claim is on the intent of North Korea. Is the president right? Is North Korea really no more of a threat than France with nuclear weapons? France has nukes. We don't worry that France will hit us any more than France worries about America.
I doubt that. And on that basis I don't think that statement should have been made. It is wrong.
On the other hand, I don't think anybody, including the president, actually believes that the nuclear threat--whether the impending North Korean capability to strike or the desire to strike--is literally over based on signing a vague statement of intent in Singapore. Obviously this is a process that will take time, as our secretary of state confirmed:
Speaking the day after an unprecedented summit between Trump and North Korean leader Kim Jong Un, Pompeo told reporters negotiations on Pyongyang's atomic arsenal could move forward quickly and would take place "most certainly in the president's first term."
"Major disarmament... We're hopeful that we can achieve that in the two and half years," he said, adding that there is "a lot of work left to do".
(And as an aside, I was wrong to expect a more fleshed out agreement to be ready for signing at the Singapore meeting, as normal practice dictates.)
If the president stating that the threat is "over" helps North Korea continue on the path of making the threat truly over in both senses, the hyperbole is acceptable. Believe me, nobody in the American military involved in fighting the nuclear threat heaved a sigh of relief and said, "Well, my job is done!"
We will see if this outreach works or if North Korea is trying to buy time to get nukes and make an American military option too dangerous to consider. And we will need to see reversal quickly--even if the process of course takes time to complete--before we are faced with the decision to strike or risk allowing North Korea to cross the nuclear weapon threshold.
*And maybe I'm just not noticing it, but the media used to be filled with speculation about when North Korea would get the ability to strike an American city. Last year the guess was sometime early this year, if memory serves me. But I don't recall reading or hearing any such estimate this year. I'm hoping that we just got better on not leaking that information and don't want the North Koreans to know the state of our knowledge. And hopefully our intelligence people accurately think we have more time than I thought we had.