Americans can expect to see “greater enforcement” of federal laws against recreational marijuana, White House Press Secretary Sean Spicer said during a press conference Thursday – signaling that the Trump Administration may be willing to put down nascent attempts at legalization that are spreading state to state.

At the same time, Spicer said President Donald Trump was supportive of a federal rule that gave leeway to states allowing medical marijuana use. But he suggested that fighting recreational cannabis use took on special importance in light of a nationwide opioid addiction crisis.

“I’ve said before that the President understands the pain and suffering that many people go through who are facing, especially, terminal diseases,” Spicer said, “and the comfort that some of these drugs, including medical marijuana, can bring to them.”

He added, though, that “there’s a big difference between that and recreational marijuana. I think that when you see something like the opioid addiction crisis blossoming in so many states around this country, the last thing we should be doing is encouraging people.”

Spicer did not immediately say how the President intended to enforce federal laws in states that had approved recreational or medical marijuana. There are 28 states that now have medical marijuana laws on the books, while eight states – including California – permit recreational cannabis.

When a reporter pressed him for clarity, he said it was “a question for the Department of Justice.”

“I do believe that you’ll see greater enforcement of it,” Spicer said.

A spokesman for the justice department told The Cannifornian they declined to comment on the matter for now.

Aaron Herzberg, an attorney and cannabis real estate investor based on Costa Mesa, said it would be unrealistic and “political suicide” for Trump to “wage an all out war” against recreational marijuana. He pointed out the millions of dollars in tax revenue flowing to states with legal cannabis laws, along with the fact that Trump advisor Peter Thiel has heavily invested in the industry.

Herzberg said he suspects Spicer’s comments are “saber rattling” more than a viable threat.

Marijuana remains illegal under federal law, but the Obama Administration largely let states carry out their own legalization schemes so long as they enforced regulations aimed at preventing sales to minors, money laundering and other criminal offenses. Thursday’s comments from Spicer were perhaps the clearest indication yet that the Trump Administration may not go so easy on legal weed states.

California Attorney General Xavier Becerra reacted to the news by saying he took an oath to enforce the laws that California has passed.

“If there is action from the federal government on this subject, I will respond in an appropriate way to protect the interests of California,” Becerra said via email.

Smart Approaches to Marijuana, which has fought marijuana legalization efforts across the nation and funded opposition to California’s Proposition 64, applauded Spicer’s comments.

“This isn’t an issue about states’ rights, it’s an issue of public health and safety for communities,” Kevin Sabet, CEO of the organization, said in a statement. “We’re hopeful that the Trump Administration will pursue a smart approach to enforcement that prioritizes public health and safety over political ideology.”

Spicer’s statement linking legal marijuana to the opioid epidemic drew immediate, sharp criticism from cannabis rights advocates.

“Spicer has it exactly backwards,” said Ethan Nadelmann, executive director of Drug Policy Alliance. “Greater access to marijuana has actually led to declines in opioid use, overdoses and other problems.”

Paul Armentano, deputy director of NORML, said the comments weren’t surprising given statements made by recently confirmed U.S. Attorney General Jeff Sessions during his vetting process. Sessions has long been an opponent of marijuana use, saying in past years that “good people don’t smoke marijuana.”

Related: Jeff Sessions: What can the new attorney general do to stop cannabis? What will he do?

Armentano pointed to polling out just hours earlier from Quinnipiac that says 71 percent of voters “oppose the government enforcing federal laws against marijuana in states that have already legalized medical or recreational marijuana.”

“In short,” he said, “undermining voters’ wishes and state laws in this regard not only defies common sense, it is also bad politics — particularly for an administration that is defining itself as populist in nature.”

The comments come as Rep. Dana Rohrabacher and three other congressional representatives from states that have legalized marijuana have formed a “Cannabis Caucus” to advance federal laws allowing cannabis cultivation, sale and use.

A group of Democratic legislators in California are also floating a bill that would make it illegal for state or local authorities to assist federal agents in going after Californians who are complying with state marijuana laws.

“I feel like what we needed most from Washington was information,” said Hezekiah Allen, executive director of the California Growers Association. “Now we have it and now we’ll have to put our heads together and figure out how to implement these (legalization) laws as quickly as possible.”

California has been working to reconcile two sets of cannabis regulations: the Medical Cannabis Regulation and Safety Act and recreational cannabis laws under Prop. 64. The state has a fast-approaching Jan. 1, 2018 deadline to implement the new laws.

Allen said the White House’s stance could cause the state to prioritize medical cannabis regulations, depending on how state leaders respond.

“It may be valuable to make sure we have a robust defensible medical marketplace and spend a little less time worrying about adult use at this point,” Allen said.

A spokesman for California’s Bureau of Medical Cannabis Regulation told The Cannifornian that Chief Lori Ajax had no comment on Spicer’s position at this time.

Marijuana Majority pointed out a 2016 clip of Trump saying in response to a question about legalizing cannabis that “medical should happen,” but then implying that laws on recreational use “should be a state issue.” However, Trump also said that “there’s a question as to how it’s all working out there” in Colorado, which fully legalized marijuana in 2014.

Marijuana Majority has already set up a petition on the official White House site, asking President Trump to follow his campaign rhetoric and leave the question of cannabis up to the states.

Eureka Times-Standard Staff Writer Will Houston contributed to this report.