The most credible arguments (IMO) are:

* National Security - we need to be able to make or trade for what we need in the case of war. Even non-tariff economists will give you this one but it can become a slippery slope. We need some capacity to make semiconductors, some steel/aluminum, pharmaceuticals, drones, etc.

* Tank the 10-year. If people pour into treasuries, the 10-year drops and we can refinance our debt a lot cheaper.

* Force a renegotiation of unfair trade agreements.

Weak arguments (IMO):

* bring back manufacturing jobs - even if we reshore some manufacturing, it'll be at the cost of many more other jobs and that manufacturing will be highly automated. No capital appetite exists to do this. No CEO wants to do this. We don't have the infrastructure or supply chains for this.

What is very difficult to defend is the implementation even if you agree with plan. No one outside the trump bubble can really defend the on-again-off-again, inconsistent communication, or board of imaginary numbers used for these. Some float "madman theory" as part of design on renegotiations but I don't think people will make deals with 'madmen' they can't trust and instead are much more likely to build coalitions against them.