China and Russia have hit back after US tariffs on $34 billion worth of Chinese goods came into effect.
US President Donald Trump threatened to impose more.
China retaliated by imposing a similar 25% tariff on 545 US products - including cars, soya beans and lobsters - also worth a total of $34 billion.
Russia is introducing extra duties on a range of products imported from the US that can be replaced by locally made equivalents.
They include road-building equipment, products for the oil and gas industry, and tools used in mining.
China's commerce ministry said it had lodged a new complaint with the World Trade Organization (WTO).
Beijing has accused the US of starting the largest trade war in economic history.