Image copyright The Blue House Image caption The rösti may not look hugely appetising, but hopefully Kim Jong-un will like it

From caviar chosen in bad taste to presidents throwing up, food has over the years played a considerable part in diplomatic get-togethers.

World leaders and politicians often work long hours, negotiate difficult situations, spend a lot of time talking to people and maybe even have a few sleepless nights. But certainly, like the rest of us, they always have to eat.

There are two big meetings between leaders this week and a lot of thought has gone into the menus.

North Korea's Kim Jong-un is meeting South Korean President Moon Jae-in in the first talks between the two countries' leaders since 2007. A flat sea fish to remind Mr Moon of his hometown port city of Busan will be served, but so too will Swiss rösti, a nod to the school years Mr Kim is said to have spent in Switzerland.

Over in the US, French President Emmanuel Macron is making the first state visit by a foreign leader under Donald Trump's presidency. The Trumps served up the best of American fare at the state dinner, with a few French touches.

Unifying menu

So is serving Mr Kim, who is believed to have a love of French cheese and wine, a Swiss dish a conscious ploy on the part of the South Koreans to win him over?

"It's certainly part of the tactics," says Johanna Mendelson-Forman, an adjunct professor at the American University in Washington DC and an expert in the field of culinary diplomacy.

"The whole menu is fascinating," says research consultant Sam Chapple Sokol, who argues that food at the summit is, literally and figuratively, setting the table for positive discussions.

"Because it calls upon all the regions of both Koreas, it's a unifying menu. So, the goal really seems to be unification on the table."

Image copyright The Blue House Image caption John Dory, a reminder of home for South Korean President Moon Jae-in

He points out that the North Korean government has never actually confirmed that Kim Jong-un lived in Switzerland, and so, "it is a little bit of a gamble, and almost an assumption on the part of the menu designers that this is the one Swiss dish to serve".

He adds: "Who knows, maybe he's never had it before, or maybe he's more accustomed to fondue or raclette."

Food faux pas

Former US Secretary of State Hillary Clinton called food "the oldest diplomatic tool" in fostering relationships. It is used in the hopes of improving co-operation but, as Mr Sokol explains, things don't always go to plan.

In 1992, then US President George HW Bush was visiting Japan as part of an Asia trip. At a state dinner, in between the second course (raw salmon with caviar) and the third (grilled beef with peppery sauce), he made history by becoming the first sitting president to vomit on the prime minister of Japan.

The food was reportedly not to blame, with US media at the time quoting the president's men as saying it was "just the flu".

Image copyright AFP Image caption Caviar. Maybe not for a socialist president

"There obviously was no malintent there," says Mr Sokol, "but I think that probably set us back a few years and he's still made fun of by people in Japan."

There are other unfortunate diplomatic examples too.

When former US President Barack Obama hosted his French counterpart François Hollande for a state dinner, the White House menu featured caviar from Illinois.

As part of a fancy state affair, this isn't unexpected. But for Mr Hollande, whose socialist government was careful not to spark further French resentment towards the wealthy "caviar left", as they were dubbed, this couldn't have been great for optics back home, according to Mr Sokol.

Breaking of bread

"Food is a tremendous, tremendous, powerful tool," believes analyst Dr Maria Velez de Berliner. "Whoever controls the access to food, they have control of the room."

This certainly proved true for UK Prime Minister Margaret Thatcher in 1979. In a European Council meeting with French President Giscard d'Estaing, who wanted to break for dinner, she refused to end the session before a decision was made.

Image copyright PA Image caption Margaret Thatcher: No food till we agree

Unsurprisingly, she managed to make Mr d'Estaing more amenable to her proposals as the evening dragged on.

Ms Mendelson-Forman argues that food in diplomatic situations also has the capacity to break down barriers.

"Food humanises people - it humanises your adversaries," she explains.

During the 20 months of negotiations for the 2015 Iran nuclear deal, tensions were high and the talks nearly collapsed at least five times, according to the New Yorker.

Negotiators had always eaten separately but on the 4th of July, America's Independence Day, the Iranians extended an invitation for the two sides to break bread together - with no shop talk allowed.

"It was the first time the Iranians and Americans looked at each other differently," says Ms Mendelson-Forman.

"They saw each other as negotiators first," agrees Dr Berliner, "and then they saw each other as people."

Within 10 days an agreement was finally reached, with both experts convinced it was made possible by the Persian meal the two sides had shared and the rapport it had helped foster.

It could be that this spirit will endure this week and in the near future.

The next big unprecedented diplomatic meeting on the calendar is Donald Trump and Kim Jong-un - could what's on their plates shape a breakthrough?