WORLD Trade Organization (WTO) Director General Roberto Azevedo expressed concern at U.S. President Donald Trump’s plan for tariffs on steel and aluminium Friday, an extremely rare intervention into a WTO member’s trade policy.

“The WTO is clearly concerned at the announcement of U.S. plans for tariffs on steel and aluminium. The potential for escalation is real, as we have seen from the initial responses of others,” he said in a brief statement issued by the WTO.

“A trade war is in no one’s interests. The WTO will be watching the situation very closely.”

Trump struck a defiant tone Friday, saying trade wars were good and easy to win, after his plan for 25-percent tariffs on steel imports and 10 percent on aluminium triggered global criticism and a slide in world stock markets.

The European Union on Friday raised the possibility of taking countermeasures, France said the duties would be unacceptable and China urged Trump to show restraint. Canada, the biggest supplier of steel and aluminum to the United States, said it would retaliate if hit by U.S. tariffs.

The plan was criticized in a WTO committee as early as June last year, and has caused an international outcry since Trump confirmed he intended to go ahead last week.

Azevedo, a former Brazilian trade negotiator, is normally extremely diplomatic and refrains from any criticism of any of the WTO’s 164 members, saying it is up to them to use the WTO’s rules and dispute settlement system to work things out.

But Trump’s tariffs plan is widely seen as being a potential threat to the system itself, since they are based on a claim to “national security,” an area that is exempt from WTO rules.

WTO member countries have traditionally refrained from citing national security, out of fear that it could provide a get-out clause from rules that have governed world trade for almost a quarter of a century.

The International Monetary Fund (IMF) also warned Friday that U.S. import tariffs on steel and aluminum would likely cause economic damage to the United States and its trading partners, and urged countries to resolve trade disputes without resorting to retaliatory measures.

“The import restrictions announced by the U.S. President (Donald Trump) are likely to cause damage not only outside the United States, but also to the U.S. economy itself, including to its manufacturing and construction sectors, which are major users of aluminum and steel,” the IMF said in a terse statement.

The IMF did not elaborate on the economic damages. It is currently in the midst of updating its global economic forecasts ahead of April meetings of its 189 member countries.

“We are concerned that the measures proposed by the United States will, de facto, expand the circumstances where countries use the national-security rationale to justify broad-based import restrictions,” IMF spokesman Gerry Rice said in the statement. (SD-Agencies)