In another long-sought concession to the US, China agreed to label fentanyl, the deadly synthetic opioid responsible for tens of thousands of American drug deaths annually, as a controlled substance.
The White House announcement framed a victory for Trump and his unflinching negotiating tactics, securing a commitment from China to engage in talks on key US economic priorities, with little obvious concession by the US.
Notably, however, the White House appears to be reversing course on its previous threats to tie trade discussions to security concerns, like China's attempted territorial expansion in the South China Sea.
"It's great the two sides took advantage of this opportunity to call a truce," said Andy Rothman, investment strategist at Matthews Asia.
"The two sides appear to have had a major change of heart to move away from confrontation toward engagement. This changes the tone and direction of the bilateral conversation."
The Trump-Xi meeting was the marquee event of Trump's whirlwind two-day trip to Argentina for the G-20 summit after the president canceled a sit-down with Russian President Vladimir Putin over mounting tensions between Russia and Ukraine.
Trump also canceled a Saturday news conference, citing respect for the Bush family following the death of former President George H.W. Bush.
Trump said Bush's death put a "damper"on what he described as a "very important meeting" with Xi.
The United States and China are locked in a dispute over their trade imbalance and Beijing's tech policies.
Washington accuses China of deploying predatory tactics in its tech drive, including stealing trade secrets and forcing American firms to hand over technology in exchange for access to the Chinese market.
Trump has imposed import taxes on US$250 billion in Chinese products — 25 per cent on US$50 billion worth and 10 per cent on the other US$200 billion.
Trump had planned to raise the tariffs on the US$200 billion to 25 per cent if he couldn't get a deal with Xi.
China has already slapped tariffs on US$110 billion in US goods.
Under the agreement reached in Buenos Aires, the two countries have 90 days to resolve their differences over Beijing's tech policies.
If they can't, the US tariff increases will go into effect on the US$200 billion in Chinese imports.
US officials insist that the American economy is more resilient to the tumult than China's, but they remain anxious of the economic effects of a prolonged showdown — as Trump has made economic growth the benchmark by which he wants his administration judged.
A full-blown resolution was not expected to be reached in Buenos Aires; the issues that divide them are just too difficult.
Growing concerns that the trade war will increasingly hurt corporate earnings and the US economy are a key reason why US stock prices have been sinking this fall.
Joining other forecasters, economists at the Organization for Economic Co-operation and Development last week downgraded their outlook for global economic growth next year to 3.5 per cent from a previous 3.7 per cent.
In doing so, they cited the trade conflict as well as political uncertainty.
The two countries also made progress on the regulation of fentanyl, which is 50 times more powerful than heroin. US officials for years have been pressing the Chinese government to take a tougher stance against fentanyl, and most US supply of the drug is manufactured in China.
White House press secretary Sarah Sanders says China's decision to label the drug as a controlled substance means that "people selling Fentanyl to the United States will be subject to China's maximum penalty under the law."
Trump met Friday with Japanese Prime Minister Shinzo Abe and Indian Prime Minister Narendra Modi in a rare trilateral meeting.
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.
Earlier that day, Trump signed a revamped three-way trade deal with Canada and Mexico, fulfilling a long-standing pledge, though the agreement could face headwinds in Congress.
- Associated Press