In response to President Donald Trump’s of tariffs to be applied to imports of steel and aluminum at some unspecified in the (presumably relatively near) future and coming from as yet unnamed nations, Japanese Trade Minister Hiroshige Seko said

I believe there is absolutely no impact on America’s national security from imports of steel and aluminum from Japan, which is an allied nation.

I agree in principle with the generally negative attitude toward tariffs.

However, Seko has misunderstood the national security question. Stipulate that Japan (and the Republic of Korea, another staunch ally and key exporter of steel to us) is a strong and reliable ally.

• Both rely on imports of raw materials in order to produce steel or aluminum
• The supply lines from raw material sources to Japan and the RoK are long, vulnerable, and easily cut off by hostile action of the PRC and/or Russia
• The supply lines from Japan and the RoK to us are long, vulnerable, and easily cut off by hostile action of the People’s Republic of China and/or Russia

Indeed, the RoK and our imports from them are even more vulnerable, with the PRC and Russia just a short hop away and the PRC’s client, northern Korea, just across a minefield.

Supply lines from other sources of our steel and aluminum imports—Canada, for instance—are much more secure.  While tariffs against nations like the PRC might be justifiable, I hope the tariffs will be suitably and tightly targeted and truly based on the illegality of dumping.

The national security question can be addressed through other means, by for instance mandating a certain amount of domestically produced steel and aluminum.  The difficult discrimination here is that the mandate must not be to “protect” American producers; they need to compete better.  The mandate must be for the demonstrable purpose of maintaining an American capability both to produce steel and aluminum and to ramp up that production capability when those supply lines get cut off.

What OPEC did to our oil supply, and so to our economy and national security, the PRC and Russia can just as easily do through our access to those metals.  And keep in mind the PRC already has attempted that with rare earth metals, which are critical to our digital capability.  One purpose of the PRC’s occupation of the South China Sea is to seize control of all those rare earth sources on the sea bottom.