My opinion: With Japan he's firming up relations. After the U.S., Japan is the number one victim of China's economic success. Until the U.S. and EU tilted the scales to China, Japan let the world in electronics. The stagnation of the Japanese economy, often attributed to the aging of their population, happened at the same time that that China's economic might exploded.
China's economy was allowed, enabled, and encouraged to grow by people and companies (e.g., Walmart) that reaped huge benefits from cheap Chinese labor, even though it decimated the U.S. economy -- and Japan's.
Trump is reminding Japan that they are a key ally, both politically and economically, and that we need to stand together against our common enemy, China -- to mutual benefit.
When Trump goes to England, he will tell the British Derps to BEHAVE -- because he has it all.
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Yes, yes, yes!
Great post.
In addition to these economic factors,
there is very strong animosity between China and Japan
dating at least to the attempted conquest of China by the
Japanese Empire known as the 2nd Sino-Japanese War (1931-1945),
wherein Japan captured Shanghai and Nanjing.
Since WWII, Japan has been crucial to the encirclement of
the USSR, and now the containment of China.
Military strategists have referred to Japan as an "Unsinkable U.S. aircraft carrier."
Japan--a great military culture--has been quietly re-militarizing
in the last few years. I'm guessing they could just about
hold their own today against China.
Japan is indeed a crucial U.S. ally; while Communist
China is our emerging enemy for the 21st century.