What could the fallout be?

Stock markets have been jittery ahead of the announcement and are estimated to have lost market value due to trade tensions.

The US tariffs announced so far would affect the equivalent of 0.6% of global trade and account for 0.1% of global GDP, according to Morgan Stanley.

The bank estimates that every $100bn of imports affected by the tariffs represents about 0.5% of global trade and 0.1% of global GDP.

Analysts are also concerned about the impact on others in the supply chain and about an escalation of tensions between the US and China in general.

Washington-based think tank the Peterson Institute for International Economics (PIIE) expects US tariffs on Chinese goods, which it says particularly target computers and electronics, to hurt multinationals more than China as well as other firms in Asia.

"China will feel some pain but not as much as these firms in the supply chain that contribute such a large share of the value added in Chinese exports," Peterson wrote.