China files a WTO complaint and Russia imposes tariffs in retaliation for US measures.
China and Russia have hit back after US tariffs on Chinese goods came into effect and President Donald Trump threatened to impose more.
China’s commerce ministry said it had lodged a new complaint with the World Trade Organization (WTO).
Meanwhile, Russia said it would introduce extra duties on a range of products imported from the US.
Beijing has accused the US of starting the “largest trade war in economic history”. What tariffs are now in effect?
US tariffs on $34bn (£25.7bn) of Chinese goods came into effect on Friday.
China retaliated by imposing a similar 25% tariff on 545 US products – including cars, soya beans and lobsters – also worth a total of $34bn.
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.
Mr Trump has already imposed tariffs on imported washing machines and solar panels, and started charging levies on the imports of steel and aluminium from the European Union, Mexico and Canada.
The US tariffs imposed so far would affect the equivalent of 0.6% of global trade and account for 0.1% of global GDP, according to Morgan Stanley. What is President Trump threatening?
The US president said America might target Chinese goods worth $500bn – the total value of Chinese imports in 2017.
The White House had previously said it would consult on tariffs on another $16bn of products, which Mr Trump has suggested could come into effect later this month.
Mr Trump said: “You have another 16 [billion dollars] in two weeks, and then, as you know, we have $200bn in abeyance and then after the $200bn, we have $300bn in abeyance.