US President Donald Trump has made golf a major symbol of his brand, both inside and outside of office.

Key points: A new book says that Mr Trump routinely cheats during his golf game

A new book says that Mr Trump routinely cheats during his golf game Celebrities and professional golf players have shared anecdotes about Mr Trump's behaviour

Celebrities and professional golf players have shared anecdotes about Mr Trump's behaviour Author Rick Reilly says that his relationship to golf speaks volumes about his Presidency

Some of his 17 golf courses have been a recurring media backdrop throughout his Presidency, and he has courted controversy by being the first President choosing to retain his courses and other businesses despite the appearance of a conflict-of-interest.

Since he assumed that role, the focus on Mr Trump's relationship with golf has reached new heights, but this has not exactly resulted in the uncritical coverage that the President often demands.

Today, a new book titled Commander in Cheat: How golf explains Trump has revealed that Mr Trump's golfing history presents a world in which bravado eschews the truth of Mr Trump's claims at sporting prowess.

Mr Trump's relationship to golf extends far, with his former caddie now his social media director. ( AP: Peter Morrison )

"To say 'Donald Trump cheats' is like saying 'Michael Phelps swims'," wrote author Rick Reilly.

"He cheats at the highest level. He cheats when people are watching and he cheats when they aren't.

"He cheats whether you like it or not. He cheats because that's how he plays golf… if you're playing golf with him, he's going to cheat."

Mr Reilly is a veteran sports writer who has been named the US Sportswriter of the Year 11 times, and his latest literary exercise saw him interview celebrities and golf stars to get a truer picture of the President's golfing habits.

And whether he's playing with luminaries in film, golf, or music, the book said Mr Trump refuses to play fair.

Security for golf matches featuring Mr Trump have heightened since he became President. ( AP: Peter Morrison )

"We clearly saw him hook a ball into a lake… and his caddy told him he found it!," said actor Samuel L Jackson.

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The book also revealed similar behaviour with stars such as Alice Cooper and LPGA player Suzann Pettersen.

"No matter how far into the woods he hits the ball, it's in the middle of the fairway when we get there," she told Mr Reilly.

Some people have speculated that Mr Trump gets away with his sporting misdemeanours courtesy of his caddie, an ex-marine in his sixties only known as 'AJ'.

The caddie spoke to Mr Reilly and said he once placed pro-level player Brian Sullivan in a chokehold during a 2017 Senior PGA Championship at a Trump golf course for disparaging comments about Mr Trump.

"Now, you listen to me, f-----! You're not gonna come to Mr Trump's course and eat Mr Trump's food and then use the word 'hate' about my president. I won't have it, you got me?," he told Mr Reilly.

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But the book also told the tale of Dan Scavino, a man who first came under the President's orbit at a golf and country club as a bag-carrier as a 16-year-old in 1990.

Today, Mr Scavino is Mr Trump's social media director, and Mr Reilly wrote that their caddie-boss dynamic is a format that extends into the machinations of the Trump administration.

"But just think of it: Mr Trump's Twitter feed is the most powerful pulpit on the globe, and Trump's former golf caddy has his hands on it, daily.

"During his 2012 campaign, Mitt Romney had 22 people approve each tweet before it went out. During the day, Trump has two — himself and his caddy. At night, just one. That's not going to change," he wrote.

Sorry, this video has expired What does Mr Trump's golf game say about him?

ABC