Japanese firms are set to scrutinize overseas deals more intently after U.S. resistance to Nippon Steel's $15 billion U.S. Steel purchase, advisers said.

Any U.S. move to block Japan's Nippon Steel would be "very unsettling," one of the front-runners to become the next Japanese prime minister said, and could dent trust between the allies.

Reports this week said that the White House is close to announcing President Joe Biden will block the $15 billion U.S. Steel deal on national security grounds.