Smartphones assembled in India accounted for 44% of U.S. imports in the second quarter, a significant increase from just 13% in the same period last year.

Meanwhile, China's smartphone exports to the U.S. shrank from 61 percent last year to just 25 percent of total U.S. imports by June. This is lower than that of Vietnam, which is now responsible for 30 percent of phone imports to the country.