Apple on Thursday trimmed its share buyback program by $10 billion, with CEO Tim Cook telling analysts that tariffs could add about $900 million in costs this quarter as the iPhone maker shifts its vast supply chain to minimize the impact of President Donald Trump's trade war.

Supply chain expert Jack Buffington joins CNN Newsroom to discuss Warren Buffett’s criticism of Trump’s tariffs amid the famed investor’s announcement that he would step down as CEO of Berkshire Hathaway at the end of the year.

Trade should not be a weapon,” the investor said as he decried policies that create a few winners and widespread resentment elsewhere.

"Trade should not be a weapon," Buffett said. He added that tariffs had "led to bad things." "Just the attitudes it's brought out. In the United States, I mean, we should be looking to trade with the rest of the world and we should do what we do best and they should do what they do best,