It happens that I know a bit of economics.
Sometime taxes / state intervention are good - market becomes more efficient: this situation is called market failure. Pollution (externality) is a typical example. Another example is moral hazard / adverse selection in many insurance markets (you americans are crazy to have such an health system: Germany pays half of what you pay in term of % GDP and has a better output - I'm talking purely in terms of efficiency, what you get for what you pay).
But a trade-war is not a market failure. There's no efficiency gain for the average Joe in having tariffs and taxes with China. The only people who gains are the stakeholders of firms protected by the tariffs. But the damage to the economy will be larger than the gains of the people who get protected.
True, there's the level the playing-field argument (which is not an argument for efficiency, the average Joe is still worst-off, but a short-term justification to force your opponent to "play fair game"). But if this is the reason of the tariffs, then tariffs should be targeted against the specific sectors where the playing field is not levelled. That's not the case with the broadband tariff-war you President has started. Easy example, Mr. Trump wants to put tariffs against EU car makers. It's very difficult to say that EU car-makers pay their employees lower wages or have less stringent anti-pollution requirements (indeed labor costs is much higher in Europe).
I have to disagree, tariffs are never a good thing. It’s basic economics that can be read in “economics in one lesson”
which you can get your free copy here