China has imposed tariffs of up to 25% on 128 US imports, including pork and wine.
It's in response to US President Donald Trump raising duties on foreign steel and aluminium imports.
The tariffs affecting some $3 billion of products - many of them agricultural - start today.
Beijing said the move was to "safeguard China's interests and balance" losses caused by new US tariffs.
The agricultural sector will be hit hardest as Kate Fisher reports from Washington.
IN: China is
OUT: already struggling
DUR: 24