Can we see signs of a trade war?

Many investors and economists believe that a trade war weakens the global economy. If this is objectively so, we should see an abnormal decline in trade between the United States, China and the European Union due to barriers to trade (tariffs, national preference). By examining recent developments in foreign trade between these three countries, the only anomaly we can see is the drop in US exports to China, probably due to China’s "hidden retaliation".