Concerns are growing due to Donald Trump's threats to impose tariffs of up to 60% on Chinese imports, which could exacerbate an already struggling Chinese economy.
Xi Jinping told Joe Biden that China would strive for a smooth transition in relations with the US.
A major trade war could affect the world economy by around 7%, equivalent to the size of the French and German economies combined.
The meeting took place in South America, a region where China has expanded its influence, which is significant for the Trump administration as it has long regarded the area as its backyard.
Scientists discovered that volcanism occurred as recently as 2.8 billion years ago on the far side of the Moon, providing new insights into the Moon's history.
The garden, part of the convent of the Church of Santissimo Redentore, was opened to the public for the first time in 500 years after a restoration project focused on sustainability and self-sufficiency.
Joe Biden has met Xi Jinping as concerns over a US-China trade war grow. Also: the discovery of ancient volcanoes on the Moon, and a secret garden in Venice is opened to the public for the first time in 500 years.