When Belgian Prime Minister Charles Michel looked back at 2017 during a talk show this week, the incident that appeared to be most noteworthy to him was his handshake with President Donald Trump.
"I was not trained, but I had prepared myself mentally," he recalled in what appeared to be half serious, half joking guidance on Trump's often-unpredictable handshake style. "I had seen on TV that [German Chancellor] Angela Merkel and [Japanese Prime Minister] Shinzo Abe had a few difficulties."
Michel was certainly not the only world leader who made learning how to deal with Trump a priority this year. Among the lessons were "the art of the super-awkward handshake." What appeared to horrify most world leaders was Trump's tendency to forcefully pull his counterparts closer toward himself during his handshakes, even though psychologists remained uncertain whether the habit was a conscious decision.
World leaders soon began to notice — and adapt.
When French President Emmanuel Macron met Trump in May, what followed was an unusually prolonged white-knuckle handshake. "My handshake with him — it wasn't innocent," Macron in a subsequent interview. "It's not the be-all and the end-all of a policy, but it was a moment of truth."
"That's how you ensure you are respected. You have to show you won't make small concessions — not even symbolic ones," Macron said.
Meanwhile, Merkel had the opposite problem when she met the president in the Oval Office in March. A visibly unenthusiastic Trump — deliberately or accidentally — ignored calls to shake Merkel's hands. The wider context of that scene wasn't lost on anyone present. Trump had previously called Merkel a "catastrophic leader" and the "person who is ruining Germany."
Merkel had intensely prepared for her meeting with Trump, according to German media reports at the time. The German leader reportedly read a number of interviews with the president to study his thoughts and world view, including an interview he gave to Playboy magazine in 1990.
Merkel had deployed the same technique earlier during her 12-year leadership whenever she sensed troubles. When Nicolas Sarkozy became French president in 2007, Merkel reportedly watched movies featuring French actor Louis de Funès. The actor was known on screen for his impatience and exaggerated exclamations — characteristics the German chancellor believed Sarkozy to have, as well.
While Merkel had a chilling reception from Trump, British Prime Minister Theresa May had to cope with the opposite. Trump and May awkwardly grasped hands in January during a brief stroll. Many observers believed that May was forced to play nice given that the country is now set to leave the European Union and relies on the United States more than almost ever before.
But the so-called special Anglo-American relationship hit a rough patch in November after Trump retweeted several anti-Muslim and anti-immigrant videos promoted by a British far-right group. Downing Street later said that it was "wrong for the president to have done this" and it remains unclear whether Trump's state visit to Britain will ever take place.
Meanwhile, in New Zealand, newly elected leader Jacinda Ardern announced during the election campaign that she would try to handle Trump like a "diplomat" to prevent an escalation of tensions.
"Despite us coming from different parts of the political spectrum, that is not new for world leaders and I have to respect democracy and the people who've chosen their leader in the United States," Ardern said back then.
But when the two first met in November, those intentions quickly derailed after she heard Trump saying about her: "This lady caused a lot of upset in her country," according to the prime minister's account of the conversation. (Ardern said that she responded by saying: "You know, no one marched when I was elected.")
Despite initial disagreements, Trump appears to have found more common ground with many male world leaders.
He watched a military parade with Macron, praised Canada's Justin Trudeau for "doing a spectacular job" and bonded with the Philippines' Rodrigo Duterte, who sang a love song for Trump during the president's visit. It came even as Trump's critics blasted the president for cozying up to Duterte, who is accused of widespread rights abuses as part of anti-crime crackdowns.
And then there's Trump's well known admiration for Russia's Vladimir Putin. All eyes, of course, are on that as 2018 unfolds.