Duchess Kate, Donald Trump and Justin Trudeau join the Queen for reception at Buckingham Palace

World heads of states that are part of NATO stepped out to Buckingham Palace on Dec. 3 for the annual dinner that is hosted by the Royal Family at the Queen's official residence. Canadian Prime Minister Justin Trudeau, US President Donald Trump and US First Lady Melania Trump were among those who joined Her Majesty, Duchess Kate, Prince Charles and Duchess Camilla at the reception.
Click through the gallery (or keep scrolling if you're on mobile) to see the best photos from the evening - along with some of the incredible style!
Photos: © Victoria Jones/AFP via Getty Images and Yui Mok/AFP via Getty Images

UK Prime Minister Boris Johnson was among the first leaders to arrive at the reception.
Photo: © Dan Kitwood/Getty Images

Here's a closer look at Melania's unique yellow and purple Valentino cape dress.
Photo: © Richard Pohle/AFP via Getty Images

Charles and Duchess Camilla also met with US President Donald Trump and US First Lady Melania Trump earlier in the day.
Photo: © Victoria Jones/AFP via Getty Images

Once inside, Canadian Prime Minister Justin Trudeau spent some time talking with Boris and Princess Anne over drinks.
Photo: © Yui Mok/AFP via Getty Images

Justin also said hello to the Queen, who was her usual stylish self in a patterned green dress with a matching scarf. She looked very pleased to see him.
Photo: © Yui Mok/AFP via Getty Images

Earlier in the day, Justin had an audience with Prince Charles at Clarence House.
Photo: © Victoria Jones/AFP via Getty Images

Anne also took some time to chat with German Chancellor Angela Merkel.
Photo: © Yui Mok/AFP via Getty Images

Once everyone had arrived, the leaders all posed for a photo with Her Majesty.
Photo: © Yui Mok - WPA Pool/Getty Images

Melania spent some time talking to the Queen after the photo.
Photo; © Yui Mok/Pool/AFP via Getty Images

Kate later dropped in and looked incredible, wearing a bespoke Emilia Wickstead dress.
Photo: © Yui Mok/AFP via Getty Images