Donald Trump's tariff announcement this week is another nail in the coffin of a global free trade ideology that had gone mostly unchallenged for decades, analysts say.

But cracks in the belief that free trade is best had been visible even before the US President pulled the trigger on steel and aluminium tariffs, and institutions defending free trade have found themselves increasingly overwhelmed by countries unwilling to play ball.

The US leader's move has compounded concerns raised in recent years by China's persistent overcapacity and Germany's chronic trade surpluses — contrary to the prescriptions of the World Trade Organization (WTO).

Other entities whose global role is being called into question are the International Monetary Fund (IMF) and the World Bank, both keystones of globalisation.

"This is effectively the Washington Consensus that is being called into question," said Ludovic Subran, chief economist at credit insurance firm Euler Hermes.

– Open borders in doubt –

The Washington Consensus refers to the neo-liberal economic policy prescriptions, including open trade and investment, that developing nations in crisis have been urged to pursue to receive help from the IMF and World Bank since the 1980s.

"Today, there is doubt that the opening of borders is always beneficial," Subran told AFP.

Triggering threats of retaliatory measures, the move on tariffs for steel and aluminium has brought the world to the brink of a trade war — which Trump said would be "good and easy to win".

"There is a problem with global governance," said one participant in major trade negotiations, on condition of anonymity.

"The WTO should be the proper tool, but it let China develop these surpluses and not respect its commitments," said the negotiator, pointing in particular to state subsidies for industry.

Even IMF chief Christine Lagarde admitted she had some sympathy for the US president's frustration with the global trade system.

Trump "has good reasons to protest against the current situation," she said on France's RTL radio, a day before the US president signed the tariff order.

"There are countries that don't always respect WTO agreements, which have technology transfer requirements, one thinks naturally of China, but China isn't the only country to have such practices," said Lagarde in a tacit acknowledgement that global trade rules haven't always been respected in recent years.

Jennifer Hillman, who previously served at the WTO adjudicating trade disputes, raised the possibility that Trump's true purpose is "to create a crisis in the WTO or… lay the groundwork for the United States to withdraw".

– Undermining the WTO –

The United States has been putting sticks into the spokes at the WTO by blocking appointment of new judges, which is causing longer delays to resolve trade disputes.

That could work to the Trump administration's advantage as it erects protectionist measures which risk falling foul of WTO rules.

"The United States may be trying to use that queue to its advantage so it never has to come into compliance," said Hillman.

Such a strategy would, in turn, frustrate other countries who hope the WTO to seek redress against the US for unfair trade measures.