Trump attacks Amazon again, says it uses Post Office as ‘delivery boy'

President Donald Trump took aim at Amazon again on Monday, tweeting that the e-commerce giant is using the U.S. Postal Service as its “delivery boy,” raising fresh questions over antitrust concerns.

Trump slammed both the e-retailer and The Washington Post—which are both owned by billionaire Jeff Bezos-saying that both companies have “gone crazy against him ever since they lost the Internet Tax Case in the U.S. Supreme Court two months ago.”

In June, the Supreme Court overturned a ruling from 1992 that previously allowed online retailers to skirt collecting sales tax because they didn’t have a physical presence in the state. But now, states have the right to collect taxes from internet sales, which is something that Trump has long called for.

“Next up is the U.S. Post Office which they use, at a fraction of real cost, as their “delivery boy” for a BIG percentage of their packages,” Trump tweeted on Monday.

“In my opinion the Washington Post is nothing more than an expensive (the paper loses a fortune) lobbyist for Amazon. Is it used as protection against antitrust claims which many feel should be brought?” he added.

Amazon shares slipped on news of the tweets but have gained 55% this year. And last week, Jeff Bezos became the world’s richest person with a net worth of around $150 billion.

Ticker	Security	Last	Change	Change %
AMZN	AMAZON.COM INC.	207.89	+2.15	+1.05%

Trump first picked a fight with Amazon last December when he blamed the e-retailer for the U.S. Post Office’s demise.

“Why is the United States Post Office, which is losing many billions of dollars a year, while charging Amazon and others so little to deliver their packages, making Amazon richer and the Post Office dumber and poorer? Should be charging MUCH MORE!” Trump tweeted last December.

A spokesperson for Amazon declined to comment on the tweets.