Trump announced on Wednesday that a US "national security" levy of 50 percent on imports of copper, a key metal for green energy and other technologies, would come into effect on August 1. In Shanghai, visitors and vendors told AFP what they think of the tariffs, "Trump is unreliable. This is definitely the case; it's unpredictable. Like the initial tariffs of several hundred percent, which were later adjusted. This is unpredictable." one visitor said. IMAGES AND SOUNDBITES