If President Donald Trump wants to go after Amazon, he's picking the wrong issue. It's China, not taxes.

On Wednesday, Amazon shares dropped 5 percent after Axios reported that "Trump has talked about changing Amazon's tax treatment because he's worried about mom-and-pop retailers being put out of business."

White House press secretary Sarah Huckabee Sanders denied later in the day that Trump has any imminent moves planned, but Trump followed up with a tweet Thursday morning that was critical of Amazon.

Taxes are messy, but that's not how Amazon is killing small retailers.

As of last year, Amazon has been collecting sales taxes in every state where one applies. Third-party sellers — those who use Amazon's platform for distribution — have to collect sales taxes in a growing number of states and, in some cases, Amazon is required to play the role of enforcer.

Trump has seemingly had it in for Amazon CEO Jeff Bezos since the presidential campaign, presumably because of how The Washington Post, which Bezos also owns, covered him as a candidate and now as president. Throughout his attacks, Trump has criticized Amazon for being a "no profit" company, bilking the United States Post Office, not paying its fair share of taxes and for supposedly having sinister ties to The Washington Post.

But Trump has yet to connect Amazon to his pet issue: trade.