Another important point is that outsourcing as-actually-implemented isn't usually seeking "efficient production," just labor arbitrage.
> If you want to promote local production, just subsidise local production. It's generally a bad idea, but the least worst by a long mile.
I'm also fine with subsidies, but often that seems more difficult to sustain politically. It seems like tariffs and subsidies go hand in hand rather than be an either/or policy (e.g. use tariffs to fund the subsidies).
Pretty much any arbitrage is an economic inefficiency being exploited, whether it's financial (information inefficiences), shipping/merchants (geographic & local preference inefficiencies), storage (time preference inefficiencies), outsourcing (labor), etc. And in the course of exploiting it, it makes the inefficiency go away.
I think the key points are 1) that's not the kind of thing the word "efficiency" typically brings to mind, and 2) there are quite valid political reasons to want to discourage that kind of "efficiency."
Whichever it is, the point is that tariffs are the worst way to coerce change in an economy. There's no guarantee they will have anything like the effect intended, because the point in the economy where they're levied (importing X) is completely different from the point in the economy we're trying to change (locally making X). Even if they do, the costs of the change can be incredibly high. If you want to promote local production, just subsidise local production. It's generally a bad idea, but the least worst by a long mile.