Some couples hug and kiss. Some like Barack and Michelle Obama even serve up the occasional high-five or fist-bump. But one of the most closely watched pairings in the world, Donald Trump and wife Melania, enjoy more formal public displays of affection like handshakes.

At an event held at an army base in Maryland, the President thanked his wife after she introduced him by shaking her hand and motioning for her to sit down.

"It's my great pleasure to introduce my husband, the President of the United States Donald Trump," a uncharacteristically upbeat Melania said as she warmed up the crowd of servicemen and women.

"Thank you, you go sit down," Trump beamed as he pumped Melania's hand while a number of troops behind the couple smirked.