WASHINGTON (TNS) — Attorney General Jeff Sessions is rescinding an Obama-era federal policy that provided legal shelter for marijuana sales in states that have allowed recreational pot, placing thousands of marijuana businesses operating legally under state law at risk of federal raids and seizures.

The Justice Department move plunged California's fledgling recreational pot market into further uncertainty, and was met with a bipartisan backlash from lawmakers in states where marijuana is now sold legally to any adult who wants to buy it.

"It is the mission of the Department of Justice to enforce the laws of the United States," Sessions said in a statement, which said the Obama-era policy that directed federal prosecutors not to target state marijuana businesses "undermines the rule of law and the ability of our local, state, tribal, and federal law enforcement partners to carry out this mission."

Sessions said the new Justice Department policy "simply directs all U.S. attorneys to use previously established prosecutorial principles that provide them all the necessary tools to disrupt criminal organizations, tackle the growing drug crisis, and thwart violent crime across our country."

Whether federal prosecutors have the resources, or even the interest, to undermine the national movement toward more permissive cannabis regulation remains to be seen. The move on Thursday to rescind the safe-harbor policy, however, is certain to spread anxiety throughout the rapidly expanding multibillion-dollar pot business in several states.

States that have legalized are girding to fight. California Attorney General Xavier Becerra had previously all but dared Sessions to initiate raids in his state, suggesting it would be a fool's errand.

"Have no doubt," Lt. Gov. Gavin Newsom tweeted on Thursday. "California will pursue all options to protect our reforms and rights."

Voters in eight states have legalized recreational use of marijuana: California, Oregon, Washington, Nevada, Colorado, Alaska, Maine and Massachusetts.

Several other states, 29 plus the District of Columbia, have legalized marijuana for medical purposes. The new Justice Department policy does not put medical marijuana at risk in the same way as recreational pot, at least for now.

A law passed by Congress strictly limits the federal government from interfering with medical marijuana sales. The 9th Circuit Court of Appeals, which has jurisdiction over federal cases in California and eight other Western states, has interpreted that law to bar any prosecutions in medical pot cases.

Sessions has sought to have the federal ban lifted, and Justice Department officials suggested their new policy could be extended to threaten medical pot as well, if the law changes or if the 9th Circuit's interpretation is overturned. They left unclear whether they might pursue prosecutions of medical pot in states outside the 9th Circuit's jurisdiction.

Justice Department officials said the policy reversal won't necessarily mean a rush of new marijuana prosecutions. But they made clear their intent was to end the "safe harbor" for the industry to operate in.

"I can't say where it will or won't lead to more prosecutions," said one senior department official who spoke on condition of anonymity to discuss the policy change. "We believe that the U.S. attorneys' offices should be opened up to bring all the cases that need to be brought."

The decisions about how aggressively to pursue cases would be left up to the U.S. attorneys, the top federal prosecutors in each federal judicial district. Trump has not yet nominated U.S. attorneys in many districts, and one leading Republican senator threatened Thursday that confirmation of future nominees may be at risk if Sessions persists in his anti-marijuana effort.

Sen. Corey Gardner, R-Colo., angrily rebuked Sessions on Thursday on Twitter, accusing him of reneging on earlier assurances that prosecutors would not be unleashed on the Colorado marijuana industry.

"I am prepared to take all steps necessary, including holding DOJ nominees, until the Attorney General lives up to the commitment he made to me prior to his confirmation," Gardner wrote.

Leaving the decision up to individual U.S. attorneys will create even more uncertainty, said Neill Franklin, executive director of the Law Enforcement Action Partnership, a group that supports more permissive drug laws.

"This is going to create chaos in the dozens of states," he said.

"If enforcement of laws are subject to the whims of individual prosecutors, no one will have any idea what is legal or what isn't — because it could change from day to day. There's no greater headache for an officer of the law than not to know where those lines stand."

Sessions began signaling long ago that a crackdown was coming, but pro-marijuana lawmakers and regulators had responded with defiance, declaring that legalization was so far along that there is little the Department of Justice could do to stop it.

The Obama administration put its policy in place in response to the legalization of recreational marijuana in Colorado and Washington state. Those rules had prevented federal prosecutors from targeting marijuana businesses operating legally under state law and allowed the recreational cannabis trade to bloom in the states where voters have legalized.