The Pew Research Center surveyed 1,000 citizens from each country. They found that 68 percent of US respondents feel they can trust Japan, compared to just 28 percent who said they cannot.
In Japan, three-quarters of respondents said they trust the United States. Regarding other East Asian countries, 49 percent of Americans polled said they trust South Korea. 30 percent felt the same for China. Just 7 percent of Japanese said they could trust China.
The researchers also asked about the atomic bombings of Hiroshima and Nagasaki. 56 percent of Americans said they were justified. 34 percent said they were not.
The majority of respondents in the US aged 65 and over approved of the bombings. But when they asked people aged 18 to 29, slightly less than half showed support.
The researchers found that 60 percent of Americans think China's rise as a military and economic power makes US-Japan relations more important.
But when asked about economic ties, 43 percent of Americans said China should be the focus, whereas 36 percent said Japan.
Bruce Stokes, the Director of Pew Research Center, said, "Americans are also very pragmatic about Asia and they know that China is a rising power and we have to deal with it. They don't trust China, but they also know that economically we have to deal with China."