The US President told a TV interviewer that he gave the order for a retaliatory strike while having dinner with President Xi Jinping at his luxury Mar-a-Lago resort in Florida last week.
Mr Trump ordered the strike in response to a deadly chemical attack by the Syrian regime in the rebel-held town of Khan Sheikhoun last Tuesday.
In an interview with Fox Business Network, Mr Trump initially appeared to confuse Syria with Iraq but quickly corrected himself.
He said: "We had finished dinner, we were now having dessert and we had the most beautiful piece of chocolate cake you have ever seen. President Xi was enjoying it.
"I was given the message from the generals that the ships are locked and loaded, what do you do? We made a determination to do it, so the missiles were on the way.
"I said, 'Mr President, let me explain something to you' - this is during dessert.
"'We have just fired 59 missiles, all of which hit by the way, unbelievable, from hundreds of miles away.'
"It's so incredible, it's brilliant, it's genius."
Mr Trump initially said the missiles were heading towards Iraq but corrected himself when prompted by the interviewer.
Mr Trump said: "So what happens is I said, 'We have just launched 59 missiles, heading to Iraq.
"Yes heading toward Syria. 'And I want you to know that.'
"Because I didn't want him to go home, we were almost finished, it was a full day in Palm Beach.
"We were almost finished. What does he do, finish his dessert and go home and then they say the guy you just had dinner with just attacked a country?"
Asked how the Chinese President reacted to the news, Mr Trump said: "He paused for 10 seconds and then he asked the interpreter to please say it again. I didn't think that was a good sign.
"Then he said to me... 'Anybody that was so brutal and uses gases to do that to young children and babies - it's ok'. He was ok with it."