A "trade war" with the United States involving new U.S. tariffs on automobile imports could reduce the level of Japan's gross domestic product by as much as 0.6 percent, the International Monetary Fund said in a simulation released Wednesday.

"In the car tariffs simulation, Japan is hit the hardest," the IMF said, given that 29 percent of Japan's exports to the United States are automobiles.

The analysis is based on a scenario in which President Donald Trump's administration invokes a 25 percent increase in tariffs on automobile imports, leading to retaliation from affected countries of equivalent size, and with manufacturers reducing investment in the wake of a temporary global shock to confidence.

It also takes into account uncertainty in the global economy in the event that the Trump administration goes ahead with a planned imposition of 10 percent tariffs on an additional $200 billion in Chinese imports and Beijing hits back with retaliation of equivalent value.

In such a worst-case scenario, the IMF projects the U.S. GDP could shrink by 0.8 percent, that of emerging Asia by 0.7 percent and that of the 19-nation eurozone by 0.3 percent.

"Simulation analysis suggests that an increase in trade tensions would come at a cost for the countries involved and the global economy," the IMF said.

"While global growth remains broadly robust, the rising wave of trade tensions, new tariffs, and counter-tariffs represents a significant downside risk for advanced and emerging markets alike."


(Cars ready for export at a port in Yokohama)

On June 29, Trump said he expects the administration to complete "in three to four weeks" an investigation into whether imports of automobiles and auto parts pose a risk to U.S. national security.

The results of the investigation could significantly affect Japanese, European and other foreign automakers if they lead to the imposition of new tariffs.

IMF Managing Director Christine Lagarde expressed concern about simmering trade tensions between the United States and its major trading partners, saying her institution's latest global growth forecast of 3.9 percent for 2019 "may be the high-water mark."

"If investor confidence is shaken by these tariffs, our simulation shows that global GDP could decrease by 0.5 percent -- or roughly $430 billion -- below the current projection for 2020," Lagarde said.

"Recent data from Europe and Asia points to a decrease in new export orders and wavering confidence among some car-exporting countries, including Germany," she said.