Mr Trump was still scheduled to meet with Chinese president Xi Jinping, but analysts were not optimistic about prospects for a major breakthrough on the two countries' trade disputes a month before United States tariffs on Chinese goods are set to ramp up.
President Donald Trump and China's Xi Jinping will sit down for a highly anticipated dinner Saturday with investors and allies eager for a truce in the trade war between the world's two largest economies.
On the G20 margins, Trump scored one victory for his "America First" agenda with the signing of a successor to the North American free trade pact NAFTA, the US-Mexico-Canada Agreement (USMCA).
"I expect (US President Donald) Trump to be very warm with him, but European leaders probably are going to be very reluctant to have their pictures taken with him".
"There's some good signs", he said. The symbolism ahead of the Xi meeting was clear: the Trump administration has looked to find common cause with both nations in countering China's regional hegemony.
From left, sitting, are Trump, Britain Prime Minister Theresa May, Turkey President Recep Tayyip Erdogan, South Africa President Cyril Ramaphosa and Mohammed bin Salman.
In Buenos Aires, Trump is also due to sit down with Putin for a bilateral meeting that has taken on added import after Russian Federation fired on and detained three Ukrainian ships in the Sea of Azov near Crimea. The European Union is also pushing for reform at the WTO.
On the G20 front, Tusk admitted the world was undergoing a "difficult moment" overall, as Trump pursues a vision at odds with the idea of collective action on trade and climate change.
Protesters have vowed mass rallies to harangue the world leaders gathering in crisis-hit Argentina, where recent violence between rival football fans raised questions about the police's ability to control unrest.
"The summit seems a nonsense to me", call centre worker Agustina Vianello, 25, told AFP.
UK's May sees Brexit deal soon as future ties text agreed
The Gibraltar issue "looks quite intractable - but nothing in the European Union is ever truly intractable", one diplomat said. May's Brussels trip resulted in the expansion of the political declaration that accompanies the 585-page divorce deal.
Boca Juniors tear-gassed after bus windows broken
Nine meetings since have ended with three draws, three River wins at La Bombonera and three Boca wins at El Monumental . However, it was later confirmed the game had been suspended until 5pm local time (8pm United Kingdom time) on Sunday.
Mueller: Manafort Has Lied To Investigators Since Plea Deal
The former Trump campaign chairman has met prosecutors at least nine times, amounting to hours of discussions about what he knows. But on Monday, Mueller's office said in a new court filing that Manafort had breached his plea deal by lying to investigators.
Trump has thrown out the traditional United States playbook on free trade since his shock 2016 election, vowing to protect forgotten workers and put "America First".
On the US side, these include advisers such as Larry Kudlow and Treasury Secretary Steven Mnuchin, who are widely seen as wanting to cut a deal, but also hawkish advisers like Peter Navarro and US Trade Representative Robert Lighthizer.
Among the key United States demands articulated by Kudlow and other officials are a halt in what it calls widespread intellectual property theft and forced transfer of technology by China.
U.S. stocks closed slightly higher on Friday on market hopes that a compromise could be reached by the two leaders.
German Chancellor Angela Merkel was to miss the summit's opening after her plane was forced to make an emergency landing in Cologne due to what she called a "serious" a technical problem. She had to take commercial flights to Argentina.
In another bilateral meeting on Friday, French President Emmanuel Macron will discuss the Renault-Nissan alliance's future with Japan's Abe, seeking to defuse a brewing diplomatic row over the balance of power inside the partnership.
Late on Thursday, Macron was defiant as he rejected those who wish to confront economic challenges by being "bellicose, isolationist and closing down borders".
Macron said he would raise the killing of journalist Jamal Khashoggi with the crown prince on the sidelines of the summit.
The G20 summit is the biggest worldwide gathering in Argentina's history but comes at a bad time for the host country as it endures a crippling economic crisis. He called the deal by its old name NAFTA, prodded Trump over USA steel and aluminum tariffs and said General Motors Co's decision to cut production and its North American workforce, including in Canada, was a "heavy blow".
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