The alpha-male handshake. The deadpan reaction from NATO leaders. The presidential push to the front of the pack.

Even if Donald Trump hasn't done a lot of public speaking during his big trip abroad, the body language of the president and those around him has spoken volumes.

Day after day, with no presidential press conferences on the schedule, Trump watchers have instead parsed the president's movements, and taken away messages that are at times painfully obvious, at times puzzling.

Put it all together, though, and the sense emerges of a president aggressively, if somewhat awkwardly, trying to assert himself on the world stage — with mixed success depending on his audience.

"Throughout the trip he looked uncomfortable and isolated, others looked surprised or distant," presidential historian Julian Zelizer of Princeton wrote in an email. "The looks capture how much of the international community is dealing with the unorthodox president who has done little to show he cares about the role of the U.S. overseas."

There was certainly any number of routine and friendly interactions between Trump and world leaders.

Montenegro's Prime Minister Dusko Markovic is seen to the right of Donald Trump at a Nato summit in Brussels (REUTERS)

But there was no mistaking the cool reception of NATO leaders who stood by with stone faces on Thursday as Trump lectured U.S. allies about the need to spend more on defence. No, heads were not bobbing as Trump intoned that he had been "very, very direct" with members of the NATO alliance in saying at they "must finally contribute their fair share."

That came on the heels of a straight-faced greeting from the pontiff. In a photo that quickly went viral, Pope Francis posed next to the president with a dour look while Trump grinned. Adding to the dissonant image, Trump's wife, Melania, and daughter, Ivanka, stood next to the president, silently staring off into the distance, their sombre expressions heightened by their all black outfits.

Pope Francis poses with US President Donald Trump, First Lady Melania Trump and the daughter of Ivanka Trump at the end of a private audience at the Vatican (AFP/Getty)

Back in Brussels, after the outdoor NATO ceremony ended, as the leaders headed to their next event, most chatted and mingled, but Trump walked alone. It was a stark contrast to the way world leaders once manoeuvred to get in the camera angle with Barack Obama when he was the new president on the block.

The scene repeated itself in Italy at the G-7 summit on Friday. After the "family photo" group shot, the other leaders convivially walked down the narrow Sicilian streets to their luncheon. Trump hung back and, minutes later, opted instead to ride in a golf cart. Later, a number of the leaders surrounded Trump, some laughing as they listened.

At the NATO group shot on Thursday Trump's move to get to the front of the pack again caused double-takes.

The president pushed himself past Montenegro's prime minister, Dusko Markovic, to get to the front of the group as the NATO leaders walked inside the alliance's new headquarters building.

Markovic gave a tense smile, and later called it a "harmless situation."

US President Donald Trump, Hungarian Prime Minister Viktor Orban and British Prime Minister Theresa May, pose for a picture during the NATO (North Atlantic Treaty Organization) summit at the NATO headquarters, in Brussels (Getty Images)

But plenty of people in the Balkans were not amused.

"It seems Donald Trump did not want that anyone overshadows his presence at the summit," said the Montenegro newspaper Vijesti.

Asked about the incident, White House press secretary Sean Spicer said he hadn't seen the encounter but noted that places were assigned for the group photo.

Earlier, Trump and new French President Emmanuel Macron had engaged in a power hand shake that came across as a meeting of alpha males when they met for the first time over lunch at the U.S. ambassador's residence in Brussels.

US President Donald Trump and French President Emmanuel Macron shake hands before a lunch ahead of a Nato Summit in Brussels (Jonathan Ernst/Reuters)

After some friendly chatter, the two gripped each other's hands so tightly before the cameras that their jaws seemed to clench. It looked like Trump was ready to pull away first but Macron wasn't quite ready to disengage.

"They're presenting themselves as equals," said body language expert Lillian Glass. "They're both alphas."

A different kind of hand-clasping — or lack thereof — also sparked chatter during the trip.

Two days in a row, the president and first lady Melania Trump failed to connect when Trump reached out to grab his wife's hand — interactions that were replayed in slow-motion and endlessly dissected online.

At a red-carpet welcome in Israel, Trump reached out to grab his wife's hand but she appeared to slap his hand away. A day later, in Rome, Trump seemed to reach for the first lady's hand just as she reached up to brush her hair aside. On Thursday, the two did hold hands as they made their way down the stairs of Air Force One on another stop in their itinerary.

Glass said the interactions left people wondering: "What is that going on in that relationship?"

There was no questioning Trump's friendly mojo with Israeli Prime Minister Benjamin Netanyahu — the two embraced repeatedly while Trump was in Israel, in a telling contrast to the strained relationship the Israeli leader had with Obama.

Netanyahu even tried to intervene when a politician in his Likud party with a reputation for inappropriate antics tried to take a selfie of the unamused-looking president by attempting to swat away Oren Hazan's arm.

For diplomats, body language can be especially important.

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Trump and wife Melania during a welcome ceremony at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump adjusts the Collar of Abdulaziz Al Saud Medal, after it was bestowed upon him by Saudi Arabia's King Salman bin Abdulaziz Al Saud at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 20 May 2017 Saudi Arabia's King Salman bin Abdulaziz Al Saud presents U.S. President Donald Trump with the Collar of Abdulaziz Al Saud Medal at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 Palestinians print posters depicting US President Donald Trump in preparations for his planned visit, in the West Bank town of Bethlehem Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump accompanied by first lady Melania Trump, his daughter Ivanka Trump and her husband White House senior advisor Jared Kushner, before delivering his remarks to the Arab Islamic American Summit in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump looks on as U.S. Secretary of State Rex Tillerson and Saudi Arabia's Crown Prince Muhammad bin Nayef exchange a memorandum of understanding Reuters In pictures: President Donald Trump on tour 21 May 2017 First Lady Melania Trump shares a laugh with a child during a visit to the American International School in the Saudi capital Riyadh Getty Images In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump holds a bilateral meeting with Bahrain's King Hamad bin Isa Al Khalifa AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers rest during preparations ahead of President Trump's landing in Tel Aviv, Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 First Lady Melania Trump makes her way to board Air Force One in Riyadh as she heads with her husband the US President to Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump board Air Force One for Israel, the next stop in Trump's international tour, at King Khalid International Airport AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers wait for the arrival ceremony of US President Donald Trump at Ben Gurion airport near Tel Aviv, Israel AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump arrive aboard Air Force One at Ben Gurion International Airport in Lod near Tel Aviv, Israel Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump disembark Air Force One on arrival at Ben Gurion International Airport AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald J. Trump and his wife, US First Lady Melania Trump are welcomed by Israeli Prime Minister Benjamin Netanyahu upon arrival at Ben Gurion Airport, in Lod outside Tel Aviv, Israel EPA In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and Israeli Prime Minister Benjamin Netanyahu sit during welcome ceremony in Tel Aviv AP In pictures: President Donald Trump on tour 22 May 2017 US First Lady Melania Trump chats wife Sara Netanyahu as US President Donald Trump chats to Israel's Prime Minister Benjamin Netanyahu during a welcoming ceremony to welcome Trump at Ben Gurion International Airport Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump delivers a speech upon his arrival at Ben Gurion International Airport in Tel Aviv Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump gestures during a press conference with Israel's President at the President's Residence in Jerusalem Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump watches as First Lady Melania Trump signs the guest book at the President's Residence in Jerusalem Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump walks with first lady Melania Trump in Jerusalem's Old City Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump visits the Western Wall, the holiest site where Jews can pray, in Jerusalems Old City Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump stands next to Rabbi Shmuel Rabinowitz at the plaza in front of the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City Reuters In pictures: President Donald Trump on tour 22 May 2017 US Secretary of State Rex Tillerson and White House senior advisor Jared Kushner leave notes at the Western Wall in Jerusalem Reuters In pictures: President Donald Trump on tour 22 May 2017 US First Lady Melania Trump touches the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City EPA In pictures: President Donald Trump on tour 22 May 2017 Ivanka Trump, assistant and daughter of US President Donald J. Trump, touches the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City EPA In pictures: President Donald Trump on tour 22 May 2017 President Donald Trump visits the Western Wall AP In pictures: President Donald Trump on tour 24 May 2017 US President Donald J. Trump arrives in a vehicle to Saint Damaso's Court for a private audience with Pope Francis in Vatican City EPA In pictures: President Donald Trump on tour 24 May 2017 Pope Francis walks past Ivanka Trump and First Lady Melania Trump on the occasion of the private audience with President Donald Trump, at the Vatican AP In pictures: President Donald Trump on tour 24 May 2017 Pope Francis exchanges gifts with US President Donald Trump during a private audience at the Vatican Getty Images In pictures: President Donald Trump on tour 24 May 2017 Pope Francis meets US President Donald Trump and his wife Melania during a private audience at the Vatican Reuters In pictures: President Donald Trump on tour 24 May 2017 Pope Francis with US President Donald J. Trump EPA In pictures: President Donald Trump on tour 24 May 2017 Pope Francis gets into is car after meeting with US President Donald Trump AP In pictures: President Donald Trump on tour 24 May 2017 President Donald Trump and his wife Melania look at the frescoed ceilings during their visit to the Sistine Chapel at the Vatican L'Osservatore Romano/Pool Photo via AP In pictures: President Donald Trump on tour 24 May 2017 US President Donald Trump security vehicles are seen in front of Air Force One before take off from Leonardo da Vinci-Fiumicino Airport in Rome, Italy Reuters In pictures: President Donald Trump on tour 24 May 2017 US President Donald Trump and First Lady Melania Trump wave to reporters before boarding the Air Force One to Brussels, at the end of a 2-day visit to Italy including a meeting with Pope Francis at the Vatican, at Rome's Fiumicino international airport AP

Israel's ambassador to the United States, Ron Dermer, is probably wishing he'd had a better poker face during the president's Jerusalem stop.

When Trump told an Israeli delegation that he had just gotten back from the Middle East — which Jerusalem is clearly part of — Dermer instinctively reacted to the flub by putting his palm to his forehead.