US tariffs on $34bn (£25.7bn) of Chinese goods have come into effect, signaling the start of a trade war between the world’s two largest economies.
The 25% levy came into effect at midnight Washington time.
China has retaliated by imposing a similar 25% tariff on 545 US products, also worth a total of $34bn.
Beijing accused the US of starting the “largest trade war in economic history”.
Two companies in Shanghai told the BBC that customs authorities were delaying clearance processes for US imports on Friday.
Earlier this year, President Donald Trump ordered the US to impose tariffs on $50bn worth of Chinese goods and the first round of these kicked in on Friday.