By Saeed Azhar, Kanchana Chakravarty and Sukriti Gupta NEW YORK (Reuters) - Wall Street's main indexes were mixed on Monday after President Donald Trump said he plans to double tariffs on imported steel and aluminum,

Experts, lawmakers, and industry people—alongside Canadian officials—have issued stark warnings about Trump's plan.

President Trump would invoke other tariff authorities if his appeal of a trade court's ruling isn't successful, Commerce Secretary Lutnick said.

The president's plan - where countries face between 11% to more than 100% tariffs on goods brought into the US - was announced in April. But the majority of the tariffs were paused by Trump for 90 days in the wake of stock market volatility.