The $14 billion deal between Nippon Steel and U.S. Steel was slated to drive a wave of major mergers and acquisitions by Japanese conglomerates late last year, but the mammoth deal has been implicated in American politics leading up to the U.S. presidential election in November.

Republican presidential candidate Donald Trump’s pledge last week to block the acquisition by Tokyo’s Nippon Steel if he were to be elected may potentially put a dent in Japan-U.S. trade in the future.