Top White House economic advisor Gary Cohn has resigned from his position. Cohn is a Wall Street banker and became a key architect of the Trump administration's 2017 tax overhaul. Cohn's resignation comes after President Trump said he would impose hefty tariffs on steel and aluminum imports. The move has been met with global backlash, affecting ties with close allies such as Canada and Mexico. It's believed that Cohn left the White House position because of his opposition to the policy. Cohn, a former president of investment bank Goldman Sachs, was among a number of Wall Street veterans tapped by Trump for senior jobs following the 2016 presidential election.