It takes nearly a decade to get a mine online, under optimal conditions. If a conflict breaks out and China embargoes the West, what's your plan then?
Question is whats more cost-effective: paying market rates to secretly stockpile, or paying for another Iraq or Afghanistan in the south china sea...
The unwritten implication is, we can do it ourselves, but the price will skyrocket as a result. I personally think that would be fine. Wait a minute and someone else will come by to yell about this the other way.