Economist Jeffrey Sachs issued a strong condemnation of President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE's trade policies on Friday, calling the new steel and aluminum tariffs the start of a "psychopath's trade war."

In an op-ed for CNN, Sachs, who runs Columbia University's Center for Sustainable Development, blasted Trump's decision this week to implement stiff tariffs on steel and aluminum imports, a move that angered top U.S. allies including Canada, Mexico and the European Union (EU).

"Trump's trade actions are blatantly illegal. They are flimsily justified as an act of national security, but this is sheer nonsense," Sachs wrote.

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"By instinct, we strive to make sense of Trump's nonsense, implicitly assuming some hidden strategy," he added. "There is none."

Sachs predicted that Trump's actions would have an overall negative effect on the U.S. dollar, and would lead to a rapid increase in the nation's debt.

"His is a psychopath's trade war," Sachs said. "The result will be to undermine the long-term role of the dollar; ratchet up the public debt; and undermine the current expansion through a spiral of protectionist measures and rising uncertainties for business."

Sachs, an internationally recognized economist who sought to be president of the World Bank in 2012, has issued harsh criticisms toward the Trump administration before. Last year, the economist took aim at Trump's inaugural speech to the United Nations General Assembly, calling his rhetoric "ugly" and "provocative."

EU heads of state and North American leaders slammed the Trump administration this week after the tariffs' announcement, calling the move an insult to long-standing U.S. allies.

"Let me be clear: These tariffs are totally unacceptable," Canadian Prime Minister Justin Trudeau said Thursday following the announcement. "Canadians have served alongside Americans in two world wars and in Korea. From the beaches of Normandy to the mountains of Afghanistan, we have fought and died together."

EU officials said they wouldn't bow to the threat of trade restrictions or concede to the U.S.

"This is not the way we do business, and certainly not between longstanding partners, friends and allies," EU Commissioner for Trade Cecilia Malmström said.

"Now that we have clarity, the EU's response will be proportionate and in accordance with [World Trade Organization] rules."