French President Emmanuel Macron has used his rare speech to the joint houses of the US Congress to denounce nationalism and isolationism.
Mr Macron said such policies were a threat to global prosperity.
He said the US had invented multilateralism and now needed to reinvent it to create a new 21st Century world order.
Mr Macron also hailed the “unbreakable bonds” of the US and France, forged in “liberty, tolerance and equal rights”.
The French president was given a three-minute standing ovation as he took his place in the chamber for his speech.
Mr Macron has developed a strong relationship with President Donald Trump, becoming the first foreign leader to be afforded a US state visit.
But the French president’s comments showed that the pair do not agree on all subjects.
Mr Macron said isolationism, withdrawal and nationalism “could be tempting” as a “temporary answer” but they “would not douse, only inflame, the fears of our citizens”.
He said: “We must keep our eyes wide open to the risks in front of us… If we open our eyes wider, we will become stronger.”
He said the UN and Nato might not be able to fulfil their mandates and assure stability if the West ignored the new dangers arising in the world.
On trade, he said that “commercial war is not the proper answer”, as it would “destroy jobs and increase prices”, adding: “We should negotiate through the World Trade Organization. We wrote these rules, we should follow them.”
Mr Trump has in the past said that trade wars are good and easily won.
Mr Macron’s wide-ranging address highlighted numerous political and cultural links, citing Lafayette, Simone de Beauvoir, Abraham Lincoln, Hemingway, Chateaubriand and both Presidents Roosevelt.