The head of the International Monetary Fund said Wednesday that no one would emerge victorious from a trade war a trade war, warning that the economic impact of US import tariffs would be serious if other countries respond with their own barriers. "If international trade is called into question by these types of measures, it will be a transmission channel for a drop in growth, a drop in trade and it will be fearsome," Lagarde said on RTL radio. On Tuesday, US President Donald Trump reiterated his plan to slap big tariffs on steel and aluminum imports, warning the European Union it would get hit with a “big tax” for failing to treat the United States well over trade matters. “The macro-economic impact would be serious, not only if the United States took action, but especially if other countries were to retaliate, notably those who would be most affected, such as Canada, Europe, and Germany in particular,” Lagarde added. Trump boasted last week on Twitter that trade wars are "easy to win" after his initial announcement of the tariffs provoked a global outcry. US allies have threatened to retaliate by slapping tariffs on US goods entering their markets. The EU is expected to detail its retaliatory measures on Wednesday. Trump’s comments have sparked cries of foul play from US trading partners and warnings from US lawmakers and businesses of the potential for a tit-for-tat trade war that could hurt the US economy. Trump has said the United States could win such a war, since it was running such a large trade deficit. “In a so-called trade war, driven by reciprocal increases of import tariffs, nobody wins, one generally finds losers on both sides,” Lagarde said, adding that she hoped that Trump would not implement the tariffs threat. "We are anxious that these are not triggered, we are urging the sides to reach agreements, hold negotiations, consultations," said Lagarde. The IMF chief said that to a certain extent she understood the US presidents frustration with the global trade system. Trump "has good reasons to protest against the current situation. There are countries that dont always respect WTO agreements, which have technology transfer requirements, one thinks naturally of China, but China isnt the only country to have such practices," said Lagarde. But she said international trade was an engine for growth, innovation and competitiveness and cautioned that any threat to trade was risky for world growth. “If world trade were jeopardized by such measures (tariffs), they would become a vector for lower growth and a slowdown of commerce. The impact on growth would be a formidable,” she said. Lagarde said she had the impression that the White House had not thought through the risks of retaliation. The Trump administration has made the World Trade Organization (WTO) a preferred target of its "America First" policy, threatening to pull the US out of the trade body it says is hampering its ability to compete. Trump’s top economic advisor Gary Cohn, seen as a voice for Wall Street in the White House, said he would resign after he lost the fight against Trump over the tariffs. The EU executive will discuss potential retaliation measures on Wednesday. It has drawn up a list of US products from bourbon to Harley Davidson motorbikes on which to apply tariffs if Trump follows imposes tariffs. French European Affairs Minister Nathalie Loiseau the EU would raise the tariff threat with the WTO. “We are not happy about this,” Loiseau told Radio Classique. “Europe can no longer afford to be naive and passive faced with this aggressive protectionism,” she said.