US election 2016: What is the big deal about Trump's hands?

The size of his hands is said to be a sore point for Mr Trump

We have all heard endless jokes about his hair and tan, but what is the big deal now about Donald Trump's hands?

This is said to be a sore point for the billionaire, and it was revived this week by rival Republican candidate Marco Rubio, who mocked his adversary's "small hands".

During the latest Republican TV debate, Mr Trump reacted, saying he was comfortable with the size of his hands - and another part of his anatomy. "There is no problem. I guarantee."

But where and how did this all begin?

In the late 1980s, the satirical magazine Spy began mocking Mr Trump as a "short-fingered vulgarian". It did not go down well with the tycoon.

"To this day, I receive the occasional envelope from Trump," says Graydon Carter, who co-founded Spy and is now editor of Vanity Fair.

"There is always a photo of him - generally a tear sheet from a magazine. On all of them he has circled his hand in gold Sharpie [permanent marker] in a valiant effort to highlight the length of his fingers," Mr Carter says.

The latest message came last year, Mr Carter added: "Like the other packages, this one included a circled hand and the words, also written in gold Sharpie: 'See, not so short!'."

Now comes Mr Rubio. He brought up the issue in a campaign rally in Virginia on Sunday.

"He is always calling me Little Marco. And I will admit he is taller than me. He is like 6ft 2ins (1.9m), which is why I do not understand why his hands are the size of someone who is 5ft 2ins."

"And you know what they say about men with small hands? You cannot trust them."

Then, on Thursday night, Mr Rubio and Mr Trump came face to face on Fox News' Republican debate, when the issue of personal attacks among candidates came up.

Mr Rubio and Mr Trump faced each other on televised debate on Thursday

Mr Rubio said his rival had "mocked everybody" with personal attacks. Then Mr Trump came in, denying it had been an issue before.

"I have to say this: He hit my hands. Nobody has ever hit my hands. I have never heard of this one."

"Look at those hands, are they small hands?" the front-runner asked. "And he referred to my hands - 'if they are small, something else must be small'. I guarantee you there is no problem. I guarantee."

In a later interview with CNN, Mr Trump said that the "joke" was only about his hands: "I have very powerful hands."