You wouldn't need to start a trade war with the entire world, including allies, to do what you're suggesting. Just targeting a few companies or a single economy would work just as well without destroying your own country's economy and your political legacy.

The tariffs and heck, electing a man like Trump, is a response to the existing situation.

1. Debt is very high and increasing at an unsustainable rate. Rather than default on debts, empires always print more money.

2. Competitiveness has gone down. In times of comfort, work ethic goes down too and a culture emerges where the working class is looked down on.

3. Economic disparity results in political polarity between the left and the right. This leads to revolutions. American revolutions tend to be fairly peaceful, but many are violent.

4. Technological advances allows for a shift in the order. New contenders have the conditions to make good use of them, which allows them to outpace the global leader.

5. Wars increase in a desperate move to hold on to power without having an economic lead. This leads to overextension and further collapse.

The tariffs are primarily a response to debt and competitiveness. Trump's election and everyone's distrust for him stems from political polarity. Many of his recent surprising actions are in preparation for a war.

The tariffs are an attempted cure to an existing problem. But like many cures, it buys time until the inevitable happens. It's not making the US more competitive. It might not cure the economic disparity.

So what you see is three things coming together: 1) admission that the US debt may not be manageable, 2) worrying long term outlook, 3) Trump's lack of diplomacy making people assume the worst