The linked article points out the U.S. has already imposed 10% tariffs on $250 billion of Chinese good, and these tariffs are due to increase to 25 percent, naturally after the mid-terms, on Jan. 1. Trump has also threatened to impose tariffs on the remaining goods imports from China, which last year were worth $505 billion.
These tariffs are on top a $2,800 tax increase for 6 percent of taxpayers, no-tax cut for 29% and potentially wipe-out the tax-cut the remaining 65 percent have been counting on (see: Why 2018 Q3 GDP Reflects Growth Stolen by the GOP from 2019, Vote Accordingly).
The stock market in known to discount the future well in advance and the declines over the last month seems to confirm Bloomberg Economics estimates that the drag on 2019 GDP growth could be about 1.5 percentage points assuming a tariff rate of 25% on all Chinese imports.