Free and not easy
The lead editorial in the Nikkei today opposes protectionism, both in general and in specific (that is, U.S. and Japan) cases:
If a certain country sets policies that benefit only its domestic enterprises, there is the possibility that its trading partners will incline toward similar protectionist measures as a countermove. If this vicious cycle is left uncontrolled, it is possible that the WTO’s non-discrimination principle, which places importance on equal competition between domestic and foreign entities, will exist in name only.
…
The United States is not the only country suffering. Global demand has contracted, and both developed and developing countries both are contending with the same sorts of under-performing organizations and manufacturers domestically. It will be no strange thing if other countries are hesitating over criticizing America because they think tomorrow it could be their hide.
Latent in all this is the danger that protectionist barriers will go up. If we shut our eyes tight against one another’s actions, cases that are essentially outside the applicability of the WTO conventions will keep piling up as faits accomplis. Even [staying carefully] outside the line demarcating governmental provisions that could conflict with the WTO conventions, there’s plenty of room to exercise grey-area judgments related to subsidies, technology barriers, quarantining, and import procedures.
Japan, of course, has its own not-so-nice history with protectionism, so the Nikkei could have warned more against economic drag rather than just focusing on retaliatory measures by trading partners.