“In other words, we don’t have a “trade agreement” with China. Our membership in the WTO allows China to work off of our tariff book.”
We signed specific tariff agreements in 1997 and 1999 with China within the WTO framework. So technically Trump is right, we do have a trade agreement with China. In 2014, the Obama administration agreed under the WTO framework to move to tariff free imports of technology products from China. That agreement does not have to be ratified by the Senate since the authority to negotiate was ceded by the Senate to the president.
http://www.latimes.com/world/asia/la-fi-tn-us-china-tech-tariffs-20141111-story.html
Fair enough, I’ll grant you the technicality. But I doubt Trump is aware it exists, much like others wondering about MFN, without knowing what it means.