The Trump administration is targeting U.S. and Chinese e-commerce sites — Amazon, Alibaba, eBay, and others — in an effort to curb an outbreak of counterfeit brand-name products.

What's happening: In a presidential memorandum today, President Trump ordered government agencies to report back by November on how to counteract an estimated half-trillion-dollar-a-year business.

The move crosses at least two major points of tension with Trump — his acrimonious relationship with Jeff Bezos, the founder of Amazon, and his trade brinkmanship with China.

least two major points of tension with Trump — his acrimonious relationship with Jeff Bezos, the founder of Amazon, and his trade brinkmanship with China. “This is a shot across the bow to those companies. If you don’t clean it up, then the government will,” Trump trade advisor Peter Navarro said in a conference call with reporters.

Counterfeiting of the biggest brand names is a major global business. Alibaba, the Chinese e-commerce platform, has had a particular problem with counterfeit goods on its Tmall site. The White House estimated that about $100 billion in counterfeiting infringes on American intellectual property.

In an op-ed today in the WSJ, Navarro said a problem is that current law doesn't effectively police e-commerce. "Alibaba, Amazon and eBay face virtually no liability when they act as middlemen for counterfeiters," he wrote.

In a statement, an Alibaba spokesman said: “We welcome this new initiative and the attention it brings to the global fight against counterfeiting. Alibaba has developed best-in-class systems to protect IP and battle the scourge of counterfeiting. This work takes place through substantial collaboration with brands, law enforcement, trade associations and consumers, both on our platforms and offline at the criminal sources of production and distribution. We look forward to further advancing the working relationship and cooperation that we have with the US federal agencies mentioned in today's order, as well as with our global commerce peers.”

Ebay and Amazon did not respond to emails.

Go deeper: Amazon's problem with fake goods