The World Trade Organization (WTO) says global economic growth is under threat as the world's economic super powers exchange tit-for-tat trade sanctions.
In its most sober assessment of the growing tariff war between the US, European Union (EU) and China, the WTO said the global system of agreed trade rules was at potentially high risk.
It said world economic growth was in jeopardy and pleaded for a de-escalation.
The threat of a tariff war was sparked after US President Donald Trump ordered tariffs on steel and aluminium imports from the EU and China.
Both China and the EU responded with the threat of import tariffs on US cars and agricultural goods totalling hundreds of billions of pounds.
Economists have warned that previous trade wars - such as during the 1930s recession - have exacerbated economic problems and that they lead to higher prices and lost jobs.