BUENOS AIRES • He didn't sit down with two of his favourite strongmen. He downgraded a meeting with one ally and postponed one with another. He exchanged icy smiles with the Canadian prime minister who had threatened to skip the signing of a trade deal with the United States and Mexico because of bitterness over steel tariffs.
And US President Donald Trump was preoccupied by legal clouds back home, tweeting angrily that there was nothing illicit about his business ventures in Russia, a day after his former lawyer Michael Cohen pleaded guilty to lying to Congress about the extent and duration of those dealings.
For Mr Trump, his first day at the summit of the Group of 20 industrialised nations in Buenos Aires was a window into his idiosyncratic statecraft after nearly two years in office. His "America First" foreign policy has not become "America Alone" exactly, but it has left him with a strange patchwork of partners at these global gatherings.
He cancelled a meeting with President Vladimir Putin, citing Russia's recent naval clash with Ukraine. Nor did he meet Crown Prince Mohammed bin Salman of Saudi Arabia though he exchanged pleasantries with the prince, whom he has pulled close despite charges of a role in the killing of journalist Jamal Khashoggi. The President did meet leaders of two Pacific allies, Australia and Japan, and the prime minister of India.
Still, in purely social terms, Mr Trump's day may well have peaked at 7.30am when he greeted Argentina's President, Mr Mauricio Macri, at the Casa Rosada. The pink presidential palace is famous for the balcony from which Argentina's former first lady Eva Peron once spoke to adoring crowds in the plaza below.
"We've known each other a long time," said Mr Trump, who was involved in a Manhattan real estate deal with Mr Macri's father in the 1980s. "That was in my civilian days," said the nostalgic President.
To some experts, Mr Trump's truncated schedule represented a new phase in his unorthodox approach to statecraft. "In previous meetings, Trump has been more focused on undermining the very notion of a global agenda, let alone affirming the US' leadership role in defining it," said Dr Vali Nasr, the dean of the Johns Hopkins School of Advanced International Studies. "But in this one, with the exception of his working dinner with Xi, he is not even doing the key bilateral meetings," he said, referring to Chinese President Xi Jinping.
Still, other former diplomats said the heavy focus on face-to-face meetings was overblown. "The President came to office believing that personal relations among leaders were a central part of international relations," said Mr Elliott Abrams, who has worked for presidents Ronald Reagan and George W. Bush. "I believe he has found that most foreign leaders will not allow personal likes or dislikes to affect policy, and that national policies are most often driven by history, geography and bureaucratic decision-making."
"So," he added, "meetings at the top often become less critical."