Leaders "do not negotiate", says Christopher Lee. (Picture: PA).
When Trump cancelled his summit with North Korea on Thursday, he was doing what all leaders - particularly American ones - have been doing since 1986, when Ronald Reagan played the same game with Mikhail Gorbachev.
No president goes to a summit without knowing exactly what will be the outcome.
The purpose of a summit is what the Americans call a "gold-pen affair". It is not a place to negotiate.
Leaders do not negotiate. That has not been done since the 1940s and Churchill, Stalin and Truman.
The negotiating is done by juniors who do talks about talks, then middle diplomats and government people who agree with each other over what is possible.
Then, team leaders, such as foreign ministers, come in and have to agree not only on what is possible, but to whether any agreement can be ratified by governments back home.
It is only once an agreement is reached at meetings, quite often in secret, that presidents can be brought into the discussion.
The proposed 12 June summit between President Trump and Kim Jong-un was nowhere near that state.
Nothing had been agreed at talks about talks to high official meetings that Mr Trump could have signed up to, and 12 June is coming too quickly, therefore Trump would have been seen as a failure.
What many missed this week is how South Korean President Moon was a key player in this.
They said North Korea had nothing that would hold water.
There were also doubts over whether Kim Jong-un would cancel at the last minute - setting up Mr Trump to look a failure and a fool.
The Americans put the gold pen back in the President’s desk tidy.
So is that it? No. We have seen summit tactics. Trump’s letter to Kim was reassuring - we’ll meet one day.
The US president is going to a NATO summit in July. He wants a tough success story on Iran and North Korea to take to that meeting. He still sees himself as a world leader without knowing what one does.
Today, someone went back to the White House history book and the year 1986, when Reagan said to the USSR’s Mikhail Gorbachev:
"Sorry, cannot make the summit. There’s nothing to sign."
They delayed and eventually met that October in Iceland. There was no big deal even then. But Reagan looked like a serious president.
Trump wouldn’t mind that from a re-scheduled Singapore.
Christopher Lee is the Forces Radio, BFBS Defence Analyst. He can be heard every week on the only radio programme devoted to discussing matters of defence and security, Sitrep. To listen head here, to download click here.