U.S. President Donald Trump, charging "Japan has been winning" on trade in recent decades, said he will push for more reciprocal trade with Washington's close U.S. ally- but in a friendly way.

Trump was speaking in Tokyo on the second day of a 12-day Asian trip expected to be dominated by North Korea and trade.

"The United States has suffered massive trade deficits at the hands of Japan for many, many years," Trump said at the start of a meeting with Japanese and U.S. business leaders.