U.S. Attorney Billy Williams on Friday said he's troubled by the overproduction of marijuana in Oregon and the black market exportation of the crop to other states, though he declined to detail how his office will carry out a new federal directive stripping legal protections for marijuana businesses.

In his first public comments since Thursday's announcement by the U.S. Department of Justice, Williams told The Oregonian/OregonLive that he's awaiting additional guidance from federal officials. He offered a cautious response, saying he doesn't "believe in overreacting."'

"I want to be methodical and thoughtful about what we do here in the District of Oregon," he said.

His answer is likely to frustrate Gov. Kate Brown, who held a press conference in front of the U.S. District Courthouse, where Williams works.

The governor vigorously defended the state's legal marijuana market and accused Attorney General Jeff Sessions of "ripping the rug out from underneath the marijuana industry," which she pointed out has generated thousands of jobs and millions in tax revenue for the state.

Brown's staff continues to press Williams for a guarantee that he won't meddle in legal pot sales and production.

"We want assurance that nobody is going after lawful Oregon businesses operating under Oregon law," Jeffrey Rhoades, Brown's marijuana policy advisor, said Friday.

State officials pointed out new state laws aimed at cracking down on the black market and additional police assigned to a law enforcement task force in southern Oregon to curb the illicit market as evidence that Oregon takes federal concerns seriously.

Sessions roiled Oregon's cannabis industry when he released a memo saying he would let federal prosecutors decide how aggressively to enforce federal marijuana law in states where the drug is legal.

Under President Obama, the federal government took a largely hands-off approach to recreational and medical marijuana provided states developed robust regulations targeting illegal distribution.

In a document known as the Cole memo, federal enforcement officials spelled out their marijuana enforcement priorities, which included cracking down on the black market, violent crime and keeping the drug from minors. Those guidelines served as a roadmap for states as they crafted rules.

Under federal law, marijuana remains a Schedule 1 drug, a category of drugs that includes heroin and is defined as substances that have a "high potential for abuse" and "no currently accepted medical use."

Oregon was the first state to decriminalize personal possession of marijuana in 1973 and legalized medical marijuana in 1998. Voters overwhelmingly approved its recreational program in 2014, becoming the third state behind Colorado and Washington to do so.

The state's industry employed more than 20,000 people last year and generated close to $450 million in sales, according to Beau Whitney, a senior economist with New Frontier Data, a market research firm.

Yet Oregon's seed-to-sale regulation of marijuana has done little to reduce the state's notorious role as a black market source, said Williams, who on Friday called it a "huge problem."

"That has been my concern for months," he said.

He questioned why Oregon has failed to contain marijuana production by limiting the number of licenses it issues. According to the latest figures from the Oregon Liquor Control Commission, the agency that regulates marijuana, the state has licensed 892 marijuana producers. The agency is in the process of reviewing another 766 applications for producer licenses.

"There is currently no cap," Williams said. "Why not?

He said he remains unconvinced that Oregon has taken adequate steps to address problems identified in a draft report obtained by The Oregonian/OregonLive last year. The report, later criticized by the governor as inaccurate and biased, concluded that Oregon has an "expansive geographic footprint" on the black market, with a half-dozen counties leading the way in supplying much of what is shipped out of state.

"I assume that has only grown in the last 12 months," Williams said.

Even as the new federal directive injected uncertainty into an already risky business, some in the industry said many entrepreneurs seem to be taking the announcement in stride.

Vince Sliwoski, a lawyer who advises Oregon marijuana businesses, said "it's full speed ahead" for his clients.

"Regardless of what Jeff Sessions does with policy guidance, I believe this ship has sailed and they'll keep doing what they are doing," Sliwoski said.

Cannabis activists also point out that Sessions seems to have galvanized a broad swath of politicians from states with recreational and medical marijuana -- Republicans and Democrats alike -- who blasted the announcement.

The policy shift was announced days after retail pot shops opened for business in California, creating what industry analysts say will become the world's largest market for legal marijuana.

Since 2012, eight states and Washington, D.C., have voted to legalize the recreational use of marijuana. A total of 28 states have legalized pot for medical purposes.

"It's just so enormous at this point," said Amy Margolis, who also advises cannabis clients in Oregon. "When you bring California online it really does feel like it's game over for federal prohibition because it's such a vast cannabis economy."

Until the Cole memo, issued in 2013, police raids of large-scale marijuana farms in southern Oregon weren't uncommon. Previous U.S. attorneys fired off letters to dozens of medical marijuana dispensaries informing them they were breaking federal laws and raising the specter of prosecution and property seizures.

Amanda Marshall, the former U.S. attorney for Oregon who resigned in 2015, said the memo prompted a clear shift in priorities away from marijuana enforcement.

Marshall said Williams is likely hearing from law enforcement officials and others around the state and in Washington, D.C., who take issue with legal marijuana.

Those perspectives, she said, are bound to shape his response.

"He has different people pushing him," said Marshall, "including his boss, Jeff Sessions."

-- Noelle Crombie

ncrombie@oregonian.com

503-276-7184

@noellecrombie