U.S. President Donald Trump directed some harsh rhetoric toward Japan on the campaign trail, but as the 100th day of his presidency on Saturday approaches, he apparently has settled for a mainstream approach to Washington's relationship with its key ally in Asia.

Faced with strategic challenges such as China's military buildup and assertive territorial claims in the East and South China seas, as well as North Korea's pursuit of a nuclear-tipped ballistic missile capable of hitting the United States, Trump is likely to value the alliance with Japan as his predecessors did, according to American scholars.

"Going forward, I do not expect the Trump administration to drastically alter the main tenets of U.S. policy toward Japan," said Steven Vogel, a professor of political science at the University of California, Berkeley.