After South Korea's high court ordered Japanese firms that used forced labor to compensate victims, Tokyo restricted exports of chemicals vital to Seoul's world-leading chip and smartphone industry in an escalation of their decades-old row.

South Korean President Moon Jae-in has said Japan's actions are politically motivated and have caused an "unprecedented emergency" for his country's export-driven economy.

At the White House, Trump said Moon "tells me that they have a lot of friction going on now with respect to trade, primarily with respect to trade. Japan has some things that South Korea wants. He asked me to get involved."

"I like both leaders. I like President Moon, and you know how I feel about Prime Minister (Shinzo) Abe. He's a very special guy also" the president added.

"So if they need me, I'm there."

The row comes with tech companies around the world already under pressure from a weakening global outlook, while the chip sector is particularly threatened by soft demand.