Story highlights "I do believe you will see greater enforcement of it," Spicer said

He was careful to distinguish between use of medical and recreational marijuana

Washington (CNN) The White House said Thursday it expects law enforcement agents to enforce federal marijuana laws when they come into conflict with states where recreational use of the drug is permitted.

"I do believe you will see greater enforcement of it," White House press secretary Sean Spicer said regarding federal drug laws, which still list marijuana as an illegal substance.

That's a reversal from the Obama administration's stance, which laid out in an official memo that the federal government wouldn't interfere in states where nonmedical use of marijuana is allowed.

That guidance was issued after two states -- Colorado and Washington -- voted to legalize recreational use of marijuana. Obama said in the immediate aftermath of those votes that the federal government had "bigger fish to fry" than cracking down on marijuana use in states where it's considered legal.

Most drug enforcement operations are carried out by state and local authorities, with little involvement by the federal government. Enforcing marijuana laws has been considered a lower priority for federal drug agents, who have remained focused on curbing narcotics trafficking and combating a nationwide epidemic of opioid abuse.

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