[tanewishly]

So I think if the US gave out good secondary benefits, a green card and good pay for experienced candidates, the lead time would be far shorter.

Sure, you'd need to train such foreign candidates in US regulations, but that ought to be a far shorter route. And I'm sure the US could afford to get half of the ATCs from $FOREIGN_COUNTRY with such a proposition. (For countries where a desire to live in the US is common, that is).

While that is totally not done wrt that foreign country: 1. Money+employment conditions could alleviate the problem significantly; 2. something flamebaity.