The world's two largest economies have been locked in a bitter trade war for more than a year, disrupting markets and supply chains. A firm deal has yet to be signed despite a series of discussions and ceasefires on tit-for-tat tariffs.
"It's been back and forth for such a long time," said Danske Bank commodities analyst Jens Pedersen. "The market will trade on a deal when and if it happens.
"We need to see some firm agreements. We had the ceasefire, which means things are unlikely to get worse, but they are still quite bad."
Metals were also under pressure from a stronger dollar, making dollar-priced commodities more expensive for buyers with other currencies.
Benchmark copper on the London Metal Exchange (LME) fell 1.3% to $5,817 am ounce by 1048 GMT, its weakest since June 17.
CHINA: China will investigate state-owned metals conglomerate China Minmetals Corp and chemicals producer China National Chemical Corp in a new round of central government environmental audits, the environment ministry said.
COPPER STOCKS: On-warrant copper stocks available in LME-approved warehouses rose 5,600 tonnes to 260,725 tonnes, their highest since June 2018. <MCUSTX-TOTAL>
COPPER SPREAD: The discount between the LME cash copper and the three-month contract <CMCU0-3> hovered around a two-week high at $17.95 a tonne, indicating ample nearby supply.
COPPER CHARGES: China's Jiangxi Copper Co and Tongling Nonferrous Metals Group have signed treatment and refining charges deals with Chilean miner Antofagasta for the first half of 2020 at $64-$70 a tonne and 6.4-7 cents a pound, sources said.
CHILE: Total copper exports from top producer Chile in June were down 14% year on year at $2.628 billion. The value of lithium exports hit $76 million, down 23% year on year.
NICKEL: The Indonesian government expects three nickel smelters to become operational in 2019, with total processing capacity of 3.9 million tonnes a year, a senior mining ministry official said.
PRICES: Aluminium eased 0.1% to $1,804 a tonne, zinc was down 0.5% at $2,367, lead gained 1.3% to $1,908, tin shed 0.8% to $18,355 and nickel dropped 0.6% to $12,635.