Saul Loeb | AFP | Getty Images
(L to R) Mexican President Enrique Pena Nieto, US President Donald Trump and Canadian Prime Minister Justin Trudeau deliver a statement on the signing of a new free trade agreement in Buenos Aires, on November 30, 2018.
Trump faces a series of diplomatic challenges over the weekend, most notably whether he can strike an agreement with Xi.
The president canceled on Putin not long after his former lawyer, Michael Cohen, revealed he had lied to Congress to cover up that he was negotiating a real estate deal in Moscow on Trump's behalf during the Republican presidential primary in 2016. The news ensured any meeting with Putin would have put a spotlight on the special counsel's investigation into whether the Trump campaign colluded with Moscow during the campaign. Trump has denied any wrongdoing.
Trump showed that the Russia investigation was testing his ability to stay focused on summit business after he blasted the investigation in a fresh tweet on Friday, again calling it a "Witch Hunt!"
One looming question is whether Trump will have a run-in with Saudi Arabian Crown Prince Mohammed bin Salman amid global dismay over the murder of Saudi journalist Jamal Khashoggi. U.S. intelligence officials have concluded that the Saudi crown prince must have at least known of the plot to kill Khashoggi, who was critical of the Saudi royal family. Lawmakers in both parties have called on Trump to at least avoid the young heir apparent as punishment.
But Trump publicly announced his decision to effectively give the prince a pass in the name of "America First," making vastly exaggerated claims of Saudi military contracts and investments in the United States. The president also views Saudi Arabia as a vital counterbalance to Iranian influence in the Middle East.
Asked Thursday why the two had no meeting scheduled, Trump said: "I would have met with him but we didn't set that one up."
With his "America First" approach, general distaste for multinational deals and habit of insulting allies, Trump typically gets a mixed reception at global gatherings.
Trump has slapped tariffs on the European Union, pulled the U.S. out of the landmark Paris Climate Accord and the Iran nuclear deal and suggested he might be willing to pull the U.S. out of NATO if member countries don't significantly boost their defense spending.