Donald Trump has hailed a trade agreement with China as "righting the wrongs of the past" as he signed the deal in Washington.
The US president also said it would deliver "a future of economic justice and security for American workers, farmers and families".
It comes after an 18-month tit-for-tat trade war between the world's two biggest economies that has threatened global growth prospects.
The "phase one" deal will roll back some tariffs and boost Chinese purchases of US goods.
It was formally unveiled at a White House signing ceremony with China's vice premier, Liu He.
Mr Trump said: "Our efforts have yielded a transformative deal that will bring benefits to both countries
"Keeping these two giant and powerful nations together in harmony is so important for the world."
But while the deal will ease tensions, it will do little to force Beijing to make the major economic changes - such as reducing unfair subsidies for its own companies - that Mr Trump sought when he started the trade war by imposing tariffs in July 2018.
At the centre of the agreement is a pledge by China to purchase an additional $200bn worth of US farm products and other goods and services over two years.
Mr Trump also said China had pledged action on the problem of counterfeit goods, and that the deal included strong protection of intellectual property rights.
The deal, which was agreed on last month, cancels planned US tariffs on Chinese-made phones, toys and laptop computers.
It also halves the tariff rate to 7.5% on about $120bn worth of other Chinese goods, including flat-screen televisions Bluetooth headphones and footwear.
But it leaves in place 25% tariffs on a $250bn array of Chinese industrial goods and components used by US manufacturers.
Mr Trump said he would agree to remove the remaining tariffs once the two side had negotiated a "phase 2" agreement.
He added that those talks would start soon - and revealed that he planned to visit China.