WASHINGTON — President Donald Trump’s administration said on Thursday for the first time that it will crack down on marijuana sales in states that have approved recreational pot use.

White House press secretary Sean Spicer said the Department of Justice will pursue enforcement of federal law against recreational use, but not medical use. The statement marked a major break with the Obama administration’s hands-off approach to the growing marijuana legalization movement.

“I do believe that you’ll see greater enforcement,” Spicer told reporters at his daily briefing. “Because again there’s a big difference between the medical use that’s very different than the recreational use, which is something the Department of Justice will be further looking into.”

The decision is certain to provoke a fight with the states that have legalized recreational marijuana. Those states are Alaska, California, Colorado, Massachusetts, Maine, Nevada, Oregon and Washington and the District of Columbia.

Jay Inslee, Washington state’s Democratic governor, made it clear earlier this month that the state would fight hard if the Trump team tried to block its recreational pot sales. “I think it would be a really big mistake for them to pick this fight, and I hope it will not occur,” Inslee said.

California legalization could translate to $5 billion in annual retail sales if Trump doesn’t intervene, according to estimates from Marijuana Business Daily. A cannabis caucus formed in Congress last week and vowed to fight Trump, if necessary, and protect legalization. Among the co-founders is Rep. Dana Rohrabacher, a California Republican and Trump supporter.

Nevada Senate Majority Leader Aaron D. Ford called on the state’s attorney general to “vigorously defend” the state’s laws.

“Not only did voters overwhelmingly vote to approve the legalization of recreational marijuana, the governor’s proposed education budget depends on tax revenue from recreational marijuana sales,” Ford said. “Any action by the Trump administration would be an insult to Nevada voters and would pick the pockets of Nevada’s students.”

Seventy-one percent of voters say the government should not enforce federal marijuana laws in states that have legalized medical or recreational marijuana use, according to a Quinnipiac University Poll released Thursday. Fifty-nine percent support legalizing recreational marijuana while 93 percent of Americans support medical marijuana use.

Washington and Colorado were the first states to legalize marijuana in 2012, while California followed suit last year. Twenty-eight states have legalized the drug for medical use.

Spicer compared the use of recreational marijuana to the opioid addiction crisis that has ravaged some communities across the nation. “The last thing we should be doing is encouraging people,” he said. He referred specific questions on enforcement to the Justice Department.

But there’s little evidence to connect marijuana to opioid addiction. In 2014, Johns Hopkins School of Public Health published a report that found in states that had legalized medical marijuana “the annual number of deaths from prescription drug overdose is 25 percent lower than in states where medical marijuana remains illegal.”

“Science has discredited the idea that marijuana serves as any kind of gateway drug, and the addiction and death rates associated with opioids simply do not occur in any way with cannabis,” said Taylor West, deputy director of the National Cannabis Industry Association.

Trump has voiced conflicting opinions about marijuana legalization through the years. At one point, during the presidential campaign, he said he supported allowing states to choose how to legislate medical marijuana. “In terms of marijuana and legalization, I think that should be a state issue, state-by-state,” Trump told reporters in 2015.