President Trump is looking to President Xi Jinping to “do something” about America’s opioid epidemic, for which he blames China.

That won’t be easy.

Buying opioids from China, despite legal prohibitions, remains as easy as providing money and a shipping address. A drug bazaar thrives on Chinese websites, providing one-stop shopping for users around the world.

On Weiku.com, a website based in the eastern city of Hangzhou, close to 100 Chinese companies say they sell fentanyl, a powerful synthetic opioid. Vendors on another site sell carfentanil, the elephant tranquilizer that is 10,000 times as potent as morphine, the New York Times reports.

Trump has accused China of being the main source of the “flood of cheap and deadly fentanyl” into America. In a news conference last week, Wei Xiaojun, a senior Chinese official, disputed Trump’s assertion, saying there was no evidence for it.

On Thursday, in an appearance in Beijing with Xi, Trump said he brought up the issue of fentanyl with his Chinese counterpart. “We’re going to be focusing on it very strongly, the president and myself,” Trump said.