Fair trade?
Why would we allow a country impose a tariff on US goods but not US impose a tariff on foreign goods. He's only imposing a reciprocal tariff. Seems fair to me.
Stepping back from the politics and rhetoric...it occurs to me that at some point it's a matter of scale.
Some countries, smaller ones, have a much smaller economy to protect, and an economy that can be much more impacted by outside impacts, while we in the US can absorb a lot more without much effect.
A decent analogy would be comparing Walmart to small local businesses. Should they be protected? What are the benefits to doing so, or to not doing so?
It's less black and white than a casual glance may indicate.