The world’s two biggest economies are now at war over trade.

China accused the United States of firing the first shot on Friday when the White House said that it would impose tariffs of 25% on $50 billion worth of Chinese goods.

"The United States has kept changing its mind and now launched a trade war," China’s Commerce Ministry said in a statement.

"China does not want a trade war," it said, adding that it would "fight back vigorously" in defense of its national interests, globalization and the world trade system.

"We will immediately launch tariff measures that will match the scale and intensity of those launched by the United States."

Beijing also said "all economic and trade agreements reached by previous negotiations will be nullified at the same time." That includes a tentative deal to increase Chinese purchases of US energy and agricultural goods.

Like the US tariffs, China’s retaliatory tariffs will be rolled out in two waves, the Finance Ministry said. And they will start on the same day.

Beijing will impose tariffs on 545 US items worth $34 billion — including agricultural products, automobiles and seafood — starting on July 6.

Tariffs on the remaining 114 items, including chemicals, medical equipment and energy products, will start later.

The United States is targeting 800 Chinese exports, worth about $34 billion, starting July 6.

Trump has long complained about China’s huge trade surplus with the United States. In a statement Friday, he said trade with China "has been very unfair, for a very long time."

The US president said the new tariffs were designed to punish China for the theft of American intellectual property and technology.

And he warned that any retaliation by Beijing would trigger another round of tariffs on Chinese goods.