With the United States and China locked in growing disputes over commerce and security that have raised questions about the future of their relationship, global financial markets next week will take their lead from the outcome of talks between Trump and Xi over dinner on Saturday.
President Trump called Saturday night's two-and-a-half dinner meeting - an hour longer than scheduled - "amazing and productive". He did not offer any details.
Trump suggested to reporters just before the sit-down that at "some point" it could yield "something that will be good for China and good for the United States".
Earlier the USA president said he had postponed a planned press conference "out of respect for the Bush family", following the death of former President George HW Bush, at the age of 94.
Washington has also accused Beijing of selling trade secrets and forcing American companies to hand over technology in exchange for access to Chinese markets.
Trump has imposed import taxes on $250 billion in Chinese products - 25 percent on $50 billion worth and 10 percent on the other $200 billion. Trudeau asked Mr. Trump to lower the newly imposed steel and aluminum tariffs.
But it was the United States and China that dominated the spotlight.
The meeting was the first face-to-face encounter between the leaders in more than a year, a period that saw Trump impose tariffs on billions of dollars in Chinese imports in a bid to force Beijing to halt trade practices the US considers unfair.
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In the latest communique, the G20 countries said that they would "safeguard against downside risks, by stepping up our dialogue and actions to enhance confidence", calling on Washington and Beijing to ease trade strains through talks.
Growing concerns that the trade war would increasingly hurt corporate earnings and the USA economy are a key reason why United States stock prices have been sinking this fall.
However, the US affirmed its "strong commitment" to economic growth and energy access and security, utilizing all energy sources and technologies, while protecting the environment. In doing so, they cited the trade conflict as well as political uncertainty.
Investors have been holding their breath about the meeting between Trump and Xi as any consensus over trade can bring some relief to global markets. Trump and the leaders of those countries signed an updated trade deal, the U.S. -Mexico-Canada Agreement, or USMCA, at the G-20.
German Chancellor Angela Merkel, also attending the G20, spoke for many when she urged progress.
Xi avoids further immediate pressure on China's slowing economy, while Trump - scarred by last month's midterm elections that saw the Democrats regain control of the House of Representatives - can ease damage to agricultural USA states that export to China, particularly soybean producers.
But the cease-fire didn't last. Trump had planned to raise the tariffs on the $200 billion to 25 percent if he couldn't get a deal with Xi. Or at least curb the strong-arm tactics.
The formal meeting has been a closely watched event leading up to the summit, as it could influence US-China trade relations.
"Perhaps we can break through in Buenos Aires or not", he said.
"We're getting along very well".