Is china or Japan closer to the US?
the pacific ocean is closer but Washington d.c. is the closest
How was the us experience establishing trade with china different from us attempts to open trade with japan?
If you consider Russia an Asian country then Russia is the Asian country nearest Alaska. China would be the next closest Asian country. And if you consider Japan, a country not on the Asian continent, Japan might be closer than China is to Alaska. The Bering Strait separates North America from Asia.
"The enemy of my enemy is my friend." Since the 1930's, Japan had been slowly conquering China. In December 1941, after Japan attacked Pearl Harbor, the US became involved in the war and started supporting Chinese efforts to fight Japan. Since the Chinese Communists were also fighting Japan, the US saw them as an ally and gave them support.