Canadians who invest in marijuana-related stocks, as well as those who use pot or work in the cannabis industry, could be banned from ever entering the U.S., according to a report Thursday.

While pot smokers and cannabis-industry workers have previously faced the prospect of lifetime travel bans, it may be news to investors that the risk extends to them as well.

Marijuana-related stocks fell in after-hours trading after Politico published the report, but managed to pare their losses on Friday. Tilray Inc. TLRY, -12.39% was last down 7% and Aurora Cannabis Inc. US:ACBFF was down 0.8%.

But Canopy Growth Corp. CGC, -8.97% fully reversed losses to gain 7% and Cronos Group Inc. CRON, -4.89% was up 6%. Valens GroWorks Corp. was up 15%. The news came after the high-flying sector’s slump this week following reports that U.S. regulators may crack down on flavored e-cigarettes.

Here's how to invest in cannabis through ETFs

According to the report by Politico, border crossings could face disruptions once recreational marijuana becomes legal in Canada on Oct. 17. While legal in several states, the U.S. federal government still classifies marijuana as a banned substance. So effectively, pot-industry workers and investors are seen as contributing to drug trafficking.

Todd Owen, a senior U.S. Customs and Border Protection official overseeing border operations, told Politico that cannabis investors from countries such as Israel have already been denied entry into the U.S. “We don’t recognize that as a legal business,” he said. “Facilitating the proliferation of the legal marijuana industry in U.S. states where it is deemed legal or Canada may affect an individual’s admissibility to the U.S.”

A CBP spokesperson confirmed marijuana-industry investors could be denied entry, and said that’s always been U.S. policy. “Generally, any arriving alien who is determined to be a drug abuser or addict, or who is convicted of, admits having committed, or admits committing, acts which constitute the essential elements of a violation of (or an attempt or conspiracy to violate) any law or regulation of a State, the United States, or a foreign country relating to a controlled substance, is inadmissible to the United States,” the agency said in an emailed statement.

Last month, BuzzFeed News reported the Trump administration was quietly ramping up its war against marijuana, and U.S. Attorney General Jeff Sessions has been outspoken in his opposition to marijuana legalization.

While Owen told Politico that customs agents probably won’t directly ask each Canadian crossing the border if they’ve used marijuana, or if they work or invest in the cannabis industry, other factors — such as a smell from a car, or marijuana residue detected by drug-sniffing dogs — could lead to further questioning.

It’s common for border agents to ask those crossing the border what they do for a living. “If you work for the industry, that is grounds for inadmissibility,” Owen told Politico. Lying to agents is also grounds for a lifetime travel ban.

The increased scrutiny will likely lead to longer wait times at border crossings and more Canadians being denied entry, especially as the legal pot industry booms.

“It’s going to happen even more, and especially now that they’re going after business travelers, it’s going to be the Wild West at the border,” Washington-state immigration lawyer Len Saunders told the Vancouver Star in July. “It’s going to be crazy.”