6 controversial moments between Queen Elizabeth and US presidents throughout history

Queen Elizabeth was reportedly jealous of the fawning attention that Jackie Kennedy received. Further drama ensued when Kennedy invited her twice-divorced brother-in-law and sister to a state dinner. The Queen initially denied their entry, causing diplomats to step in and negotiate, according to the Washington Post.

The Queen relented, but left her sister Princess Margaret and her aunt Princess Marina off the guest list since Kennedy wanted to be photographed with them.

"The queen's resentment was real," Kitty Kelly wrote in her book "The Royals."

A fictionalized version of the tense visit was portrayed on the second season of Netflix's "The Crown."

"I took a sharp step backwards – not quite far enough," the Queen Mother is said to have remarked after the encounter, according to BBC.

Michelle Obama wrote in her memoir, "Becoming," that when she met Queen Elizabeth in 2009, they bonded over both wearing uncomfortable high heels.

"Forget that she sometimes wore a diamond crown and that I'd flown to London on a presidential jet; we were two tired ladies oppressed by our shoes," she wrote. "I then did what's instinctive to me anytime I feel connected to a new person, which is to express my feelings outwardly. I laid a hand affectionately across her shoulder."

She didn't realize until later that she had committed "what would be deemed as an epic faux pas," as one isn't supposed to touch the Queen.

"If I hadn't done the proper thing at Buckingham Palace, I had at least done the human thing," she wrote. "I daresay the Queen was okay with it, too, because when I touched her, she only pulled closer, resting a gloved hand lightly on the small of my back."

Bowing or curtsying isn't necessary when greeting a royal, but the royal family's official website says that "many people wish to observe the traditional forms." Trump broke from tradition by opting for a handshake instead of a bow.

Trump also walked in front of the Queen and appeared to cut her off, which is considered a breach of royal protocol, according to The New York Times.

On the first day of President Donald Trump and first lady Melania Trump's visit to the UK in 2018, Queen Elizabeth wore a brooch given to her by Barack and Michelle Obama.

When she actually met with Trump, she wore a brooch that her mother wore to her father's funeral, which some thought could be a subtle sign of the Queen's opinion of the president.

Queen Elizabeth wore her Burmese Ruby Tiara to a state dinner at Buckingham Palace held in the Trumps' honor. The tiara contains 96 rubies that were given to the Queen as a gift from the people of Burma (also known as Myanmar).

The Queen's choice of the tiara, which is said to be a "symbol of protection against illness and evil," sparked theories among some Twitter users that she wore it purposely to dine with Trump.