OMAHA, Nebraska — Warren Buffett on Saturday criticized President Donald Trump's hardline trade policy, without naming him directly, saying it's a big mistake to slap punitive tariffs on the rest of the world."Trade should not be a weapon," Buffett said at Berkshire Hathaway's annual shareholder meeting. "The United States won. I mean, we have become an incredibly important country, starting from nothing 250 years ago. There's not been anything like it.""It's a big mistake, in my view, when you have seven a ...