Normally a North Korean missile test would attract no more than ritual condemnation from world capitals. But this time the hermit kingdom has made itself an early test of Donald Trump's judgment. The missile was fired across the Korean Peninsula in the direction of Japan on Sunday and it would have been no coincidence that Trump was hosting a state visit by Japan's Prime Minister, Shinzo Abe, at the time.
The new President's response was suitably measured. Initially he declined to answer reporter's questions on the test, which suggests he wanted to be properly briefed first. Then, a joint press conference with Abe, who called the missile launch "absolutely intolerable", Trump said, "I just want everybody to understand and fully know that the United States of America stands behind Japan, its great ally, 100 per cent."
That restrained statement was no more than any US President would have made and it was encouraging to hear it in this President's characteristic phrases.
His restraint was all the more welcome for the fact that some analysts were suggesting the missile being tested could be the first stage of an intercontinental ballistic missile capable of reaching the Unites States.
In a New Year address, the North Korean leader, Kim Jong Un, said his country "had entered the final stage of preparation" for an ICBM capable of reaching the US. In response at that time, President-elect Trump tweeted, "It won't happen".
Since taking office, his Administration is said to have begun a review of the Obama Government's policy of "strategic patience" toward the world's most unpredictable regime.
The US certainly can take its time. Analysts say the latest launch was probably a medium range missile that North Korea was trying to perfect last year. Even if they succeed its maximum range would not quite reach Alaska, the closest part of the North American continent. So they have some way to go to fulfil Kim Jong Un's inflated claim at New Year.
But that of course is no comfort to South Korea and Japan, the two countries well within range of the North's rockets and the main targets of its leaders' resentments. But any increased level of threat to either of them would be bound to invite a US response.
North Korea may have done a favour for all US allies by reminding Trump that strategic threats are real and need to be countered. There has been no tweets from the White House demanding greater financial contributions from allies in Northeast Asia this week.
Likewise, the incident is a reminder to the new President that good relations with China matter. China feeds North Korea. It might not be doing enough to stop Kim's mischief for the West's liking, but China is the key to containing him. Trump needs to consider this before he next tweets about Taiwan, trade and currency manipulation, or the South China Sea.
But to give him his due, he has not responded to North Korea's first provocation in the way many probably feared. North Korea is no more than a nuclear-armed annoyance to the neighbours. It is a test of a US President's ability to keep a cool head and let patience prevail.