During last year's election campaign, you'd sometimes hear Republicans say that in contrast to that feckless and weak Barack Obama, Trump is so strong, so resolute, so virile that our enemies would get one look at him and retreat in fear, never to bother us again.
Trump himself said some version of this many times, not just in general but with regard to North Korea specifically.
A few weeks before taking office, he tweeted, "North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won't happen!" Well, now it has happened, apparently because Kim Jong Un does not whimper in terror at the thought of being put in his place by Trump.
Up until now, the Administration's approach to North Korea has been a combination of public chest-thumping and hope that China would take care of the problem for us.
In April, Trump met with Chinese Premier Xi Jinping and apparently believed that once he presented Xi with a truly spectacular piece of chocolate cake the premier would put a prompt end to North Korea's nuclear ambitions.
Xi attempted to educate Trump on the complexities of the situation. "After listening for 10 minutes, I realised it's not so easy," Trump said.
But as we've seen in other areas such as healthcare, while Trump can be disabused of his childishly simplistic view of a policy challenge, his newfound appreciation for the complexity of an issue will only be temporary.
Before long, he goes right back to thinking there are easy solutions to every problem.
Just a few days later, Vice-President Mike Pence went to South Korea and issued stern warnings to Kim Jong Un about how strong and resolute Donald Trump is.
"North Korea would do well not to test his resolve," Pence said, then went to the DMZ and stared manfully at North Korean territory while the cameras clicked away.
"I thought it was important that people on the other side of the DMZ see our resolve in my face," he said afterward.
The Administration didn't place all its hopes in the power of Pence's face, however.
Whenever the subject of North Korea came up, Trump and members of his Administration would repeat that "the era of strategic patience is over", without saying exactly what era we're in now.
A week ago the Administration imposed sanctions on Chinese companies doing business with North Korea, but that didn't have a transformative effect on China's perspective.
Then when Tuesday's launch happened, the President responded with typical thoughtfulness: "North Korea has just launched another missile. Does this guy have anything better to do with his life?
"Hard to believe that South Korea and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense once and for all!"
It's hard to tell what kind of "heavy move" Trump thinks China might put on North Korea, and I doubt he knows himself. The unfortunate fact is that we have no good options here. We can threaten a strike against North Korea, but the result of that would be massive casualties in South Korea.
The New York Times described the problem: Even the most limited strike risks staggering casualties, because North Korea could retaliate with the thousands of artillery pieces it has positioned along its border with the South.
Though the arsenal is of limited range and could be destroyed in days, US Defence secretary, Jim Mattis, recently warned that if North Korea used it, it "would be probably the worst kind of fighting in most people's lifetimes".
That's not to mention the fact that if Kim truly thought he was about to overthrown, he might unleash whatever nuclear weapons he has, along with any other weapons of mass destruction the country possesses.
The idea that Kim will voluntarily halt his missile and nuclear weapons programmes because the President sent some more tough talkin' tweets and the Vice-President made his resolute face seems highly unlikely.
Given the fact that a military strike from the US could set off another Korean War, negotiations with the North seem like a logical part of the solution, but there are some reasons why that might not happen.
We don't have much diplomatic capability these days; the US State Department is barely functioning, and the Trump Administration has not even bothered to nominate someone to be ambassador to South Korea.
And it's clear that the President, for all his talk of deal-making, sees negotiation with other countries as a sign of weakness.
There are some things we can do to increase economic and diplomatic pressure on North Korea, but to be really effective they require the co-operation of other countries.
Trump has made that much more difficult with the contempt he has shown for the very idea of international co-operation, by belittling Nato and pulling out of the Paris climate accord. There aren't many countries that are going to join the US in a combined effort just because we ask.
It's also important to understand that as much as we see Kim as a lunatic or a buffoon, if his goal is the survival of his regime, pursuing nuclear weapons and the ability to deliver them is perfectly rational.
After all, Saddam Hussein didn't have them, and look what happened to him. The higher the cost of a military strike against North Korea, the safer he'll feel.
As the US military commander on the Korean Peninsula said on Wednesday in a joint statement with his South Korean counterpart, "Self restraint, which is a choice, is all that separates armistice and war."
Can President Trump exercise that restraint? What happens when in a moment of anger he suggests a military strike? Will his saner advisers be able to reign in his worst impulses? How important will it be for Trump to save face and look strong?
Given his thin skin, how much of an impact will personal attacks from Kim and criticisms at home have on his decision-making? How will he react when faced with a choice between two bad options?
This isn't a full-blown crisis yet. But it could become one, and for the first time President Trump will be truly tested. He hasn't done a lot to inspire confidence so far.
