For long, open and free trade across borders had been the cornerstone of any trade meeting and has been essential to keep the global economy ticking over.
In a first taste of what Trump's presidency means for the world economy, the G20 failed to get Washington to sign off on a traditional pledge to reject protectionism at a meeting in Baden-Baden, Germany.
The US is nudging the G-20 to change course.
For Washington, the watered-down language that emerged in their communiqué ensures the US can still use sanctions or other policy tools to punish trade partners and thwart economic policies the Trump administration believes to be unfair. The G20 summit with each country's government leader will be held in July in Hamburg, Germany.
China, which joined the World Trade Organization in 2001, is the biggest victim of trade protectionism, with 119 trade remedy probes totaling $14.3 billion launched against it by 27 countries and regions last year, a jump in value of 76 percent year-on-year, according to China's Ministry of Commerce. "Having said that, we want to re-examine certain agreements", he continued, speaking specifically about NAFTA.
This was replaced with a watered-down pledge to "strengthen the contribution of trade to our economies" - language viewed by some participants as preserving US flexibility on trade policy.
Treasury Secretary Steven Mnuchin refused to agree to a communique that called for resisting "all forms of protectionism".
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Belgium's Finance Minister Johan Van Overtveldt said he was "very worried" about the move toward protectionism.
"We are working to defend the multilateral rule-based system that has safeguarded our prosperity over so many decades", EU Trade Commissioner Cecilia Malmstrom said in a speech in Toronto on Monday.
"I think Mnuchin is an articulate, constructive and pragmatic man", Moscovici said.
For some, the Brexit process (and forging of new trading relations with Europe and the wider world) is a salvage operation: making the most of a bad situation.
"We met at a time when the global economic recovery is progressing".
While delegates greeted Mnuchin and said that he had been engaged in the process, they said he didn't elaborate on how the US considers itself to be treated unfairly.
"It is not that we were not united", German finance minister Wolfgang Schaeuble said.