After their hotly anticipated dinner meeting in Buenos Aires, Argentina, on the sidelines of this year's G20 leaders' summit, US President Donald Trump and his Chinese counterpart Xi Jinping found the necessary ingredients for what amounts to a temporary truce.

On Trade, President Trump has agreed that on January 1, 2019, he will leave the tariffs on $200 billion worth of product at the 10% rate, and not raise it to 25% at this time.

After signing a revamped trade pact Friday with Mexico and Canada on better terms for the United States, Trump agreed with Xi on Saturday to work to resolve issues such as forced technology transfer and intellectual property protection in exchange for suspending new US tariffs on Chinese imports for 90 days.

A statement from White House press secretary Sarah Sanders noted that China has agreed to start purchasing agricultural products from United States farmers "immediately". Wang Yi, China's top diplomat, told reporters that the negotiations had been conducted in a "friendly and candid atmosphere".

The dinner between Trump and Xi lasted almost two-and-a-half hours - an hour longer than expected, according to the South China Morning Post.

On Sunday, China's state-run media lauded the "important consensus" reached by the two leaders but did not mention the 90-day deadline.

Western businesses routinely say that Beijing's reform promises are not worth the paper they are printed on, accusing China's government of perpetually delaying substantive reforms or actively backsliding. If those negotiations aren't successful, then it's tariff time.

"It goes down, certainly - if it happens, it goes down as one of the largest deals ever made", Trump told reporters aboard Air Force One as he returned from Argentina. That will resonate on the markets when trading in "black gold" resumes on Monday, as will the ceasefire to Trump's trade war with China.

"China's trade and investment practices have prevented USA companies from competing on a level playing field and hurt US workers".

Ahead of what was seen as the most important meeting of US and Chinese leaders in years, both sides said differences remained, and the outcome of the talks were uncertain. Personal chemistry between President Trump and foreign leaders - in this case China's President Xi Jinping - and Mr Trump's appetite for deal-making matter more than painstaking negotiations at the level of senior officials.

Trump has imposed tariffs on US$250 billion in Chinese products.

They include attempts to secure the denuclearisation of North Korea and China's increasingly self-confident expansion of military power, especially in the South China Sea.

Trump, who campaigned in 2016 on cracking down on what he called Chinese trade abuses, comes into the meeting with a specific set of demands.

Beyond trade, Xi also agreed to designate the drug fentanyl as a controlled substance, the White House said.

China "is open to approving the previously unapproved" deal for USA company Qualcomm Inc to acquire Netherlands-based NXP Semiconductors "should it again be presented".

China "is open to approving the previously unapproved" deal for US company Qualcomm Inc (QCOM.O) to acquire Netherlands-based NXP Semiconductors (NXPI.O) "should it again be presented", the White House statement said.

What they agree on - or do not - will likely determine whether stock markets rise or fall and whether the world economy gets some relief from destabilizing trade tensions, as well as cast judgement on the wisdom of the United States leader's hard-nosed trade tactics. The presidents have come to an agreement on stopping the imposition of additional tariffs.

Results achieved at the meeting will not only benefit the two countries and the two peoples, but also be conducive to the global economy's stable growth, he said.

"We'll be discussing trade". And he's threatened to expand tariffs to virtually everything China ships to the United States. It was the first face-to-face meeting between the two leaders since Trump's China visit in November previous year. "It was the weakest communique we've ever seen from the G20", he told AFP, contrasting the group's posture now in the Trump era to its sense of common goal when the leaders first met 10 years ago in the midst of a financial crisis.

"Facts show that joint interests between China and the United States are greater than the disputes, and the need for cooperation is greater than frictions", he said. The European Union is also pushing for sweeping changes to how the WTO operates.

European officials said a reference to refugees and migration - a sensitive issue for Trump's administration - was excised to ensure consensus.

It said signatories to the Paris Agreement reaffirmed that the Paris Agreement is irreversible and commit to its full implementation, while the USA reiterated its decision to withdraw from the Paris Agreement.

It comes as International Monetary Fund (IMF) director Christine Lagarde urged G20 leaders to urgently de-escalate trade tensions and reverse tariff hikes.

In other key results from the talks, the US promised to uphold the one-China policy, Wang said, while China threw its support behind further meetings between Trump and North Korean leader Kim Jong Un. "China will be buying massive amounts of products from us". G20 summit host Argentina is expected to sign a series of deals with China on Sunday during a one-day state visit by Xi.

Aside from trade and climate change, Russia's seizure of Ukrainian vessels drew condemnation from G20 members. The Russian leader had a more productive dialogue in Buenos Aires with Saudi Crown Prince Mohammed bin Salman.