Updated

France's presidential hopeful Manuel Valls, who seeks the Socialist nomination, has pledged to tax U.S. imports if President Donald Trump pulls his country out of the global climate deal reached in Paris in 2015.

Valls proposed a carbon tax on American goods while speaking Monday on RTL radio. He said: "When Donald Trump declares some kind of economic war on Europe, we must be ready."

Valls, a former prime minister, is facing ex-government member Benoit Hamon in the country's Socialist presidential primary runoff Sunday.

Hamon said environmental and climate issues are among his priorities.

During his campaign, Trump suggested he was keeping an open mind about climate change and about whether he'll pull the U.S. out of the global emissions-cutting deal struck in Paris.