President Donald Trump says he will also impose "reciprocal tariffs" on any countries who place tariffs on the US.

Trump told reporters aboard Air Force One that the tariffs, which he will announce on Monday, will apply to "any steel coming into the United States," adding this will also affect aluminum.

The US president also said he will announce reciprocal tariffs on Tuesday or Wednesday, to take effect almost immediately, applying them to all countries and matching the tariff rates levied by each nation.

Shortly after tariffs on China imposed by U.S. President Donald Trump took effect on Tuesday, China's Finance Ministry said it would impose levies of 15 per cent on imports of U.S. coal and LNG and 10% per cent for crude oil as well as on farm equipment and some autos,

President Donald Trump has paused imposing tariffs on small-value packages arriving from China, apparently to give federal agencies time to sort out how to process millions of such shipments that have come through the U.