U.S. President Donald Trump listens to participants during an event at which he announced a grant for a drug-free communities support program in the Roosevelt Room of the White House in Washington, U.S., August 29, 2018. REUTERS/Leah Millis/File Photo

WASHINGTON (Reuters) - U.S. President Donald Trump threatened in an interview with Bloomberg News on Thursday to withdraw from the World Trade Organization if “they don’t shape up,” in his latest criticism of the institution.

Such a move could undermine one of the foundations of the modern global trading system, which the United States was instrumental in creating.

“If they don’t shape up, I would withdraw from the WTO,” Trump said.

Trump has complained the United States is treated unfairly in global trade and has blamed the WTO for allowing that to happen. He has also warned he could take action against the global body, although he has not specified what form that could take.