The Drug Enforcement Administration (DEA) has quietly revealed that it plans to decide within the next three months whether marijuana should be removed from the list of Schedule I controlled substances, a restrictive classification reserved for what the US government considers to be the most dangerous class of drugs.

While 23 states and Washington, DC now allow some form of medical marijuana, weed remains in the tightly-regulated Schedule I category alongside heroin, LSD, ecstasy, and other drugs deemed to have no accepted medical use and a high potential for abuse. Cocaine and methamphetamine are among the drugs listed below marijuana in the less restrictive Schedule II category.

The DEA's announcement was buried on the fifth page of a 25-page memo it delivered on Monday in response to a letter sent last July by Massachusetts Senator Elizabeth Warren and seven other Democratic senators. The lawmakers had questioned the DEA and other federal agencies about their efforts to advance medical marijuana research. The DEA said it "hopes to release its determination in the first half of 2016," but did not include any indication about whether it would ultimately move pot to a lower status on the five-rung classification ladder.

The memo, which was first spotted by Matt Ferner of the Huffington Post, also revealed that the Food and Drug Administration (FDA) has completed a scientific and medical analysis on the safety and effectiveness of cannabis, and submitted its rescheduling recommendation to the DEA. There was no mention of what the FDA's advice entailed. The DEA did not respond to a VICE News inquiry about the memo, and a spokesman for the FDA said the agency "isn't able to comment on the status of that review or any recommendations that would arise from it."

Tom Angell, founder of the advocacy group Marijuana Majority, told VICE News he is "guardedly hopeful" the government will favor a rescheduling of the drug to a lower classification.

"It's potentially hugely significant, but also potentially hugely disappointing," he said. If FDA and DEA are willing to take an objective look at the science, they'll have to come to the conclusion that marijuana does not belong in Schedule I, it obviously has medical value."

'It's potentially hugely significant, but also potentially hugely disappointing.'

In recent years, calls for rescheduling cannabis and allowing broader medical research on the efficacy of the drug have come from doctors, patients, and marijuana policy change advocates alike. Even US Surgeon General Vivek Murthy suggested last year that the drug could have benefits for some medical conditions. Millions of patients in Colorado, California, Oregon, Washington, and other states where medical marijuana is legal, use the drug and its extracts to treat multiple sclerosis, epilepsy, the side effects of chemotherapy, and a wide variety of other conditions. Marijuana remains illegal in all forms under federal law.

Opponents of marijuana legalization, including top DEA officials, have argued that there's no hard evidence that proves marijuana has legitimate medical benefits. Chuck Rosenberg, the acting head of the DEA, went so far as to call the idea of medical marijuana a "joke" last November.

"What really bothers me is the notion that marijuana is also medicinal — because it's not," Rosenberg said in a briefing to reporters. "We can have an intellectually honest debate about whether we should legalize something that is bad and dangerous, but don't call it medicine — that is a joke."

The remarks were met with heavy criticism, and more than 150,000 people signed a Change.org petition calling for President Barack Obama to fire Rosenberg.

Researchers and medical marijuana advocates have pointed out that keeping marijuana in the restrictive Schedule I category creates a sort of catch-22, where scientists can't definitively prove or disprove the drug's efficacy in treating certain conditions because of the difficulties they face in conducting clinical research.

Watch the VICE News documentary Inside America's Billion-Dollar Weed Business: The Grass Is Greener

At the moment, researchers must jump through numerous bureaucratic hoops in order to legally get their hands on marijuana. In its memo, the DEA said that the government had only provided marijuana to an average of nine research teams a year for the last five years. Moving marijuana to the Schedule II category would eliminate many of the obstacles that researchers face when procuring the drug, and also make it easier for them to obtain funding.

The DEA has not been friendly to the idea of rescheduling the drug in the past. The agency evaluated two petitions in 2001 and 2006, but ultimately decided to keep the drug as in the Schedule I category. Another petition was denied in 2011.

"Every other time in the past the DEA has had a rescheduling petition before them in the past they've denied it, so there's not a strong history here to be optimistic about," said Angell, the medical marijuana advocate. He noted, however, that the political climate surrounding marijuana has changed significantly over the past five years, and that many staunchly conservative states — including Alabama, Mississippi, Oklahoma, and Texas — now allow the use of cannabidiol (CBD), a non-psychoactive extract that usually comes in oil form. "We're in a whole different world now," Angell said.

While the DEA said it intends to make its decision soon, it's under no obligation to stick to the mid-year timeline. Congress could also move to reschedule marijuana independently of the DEA, but the chances of that happening are slim to nil. Hillary Clinton, the current frontrunner for the Democratic presidential nomination, has called for moving marijuana to the Schedule II category, while her rival Bernie Sanders has said he would remove it from list of controlled substances entirely, a move that would effectively legalize weed nationwide. Republican candidates Donald Trump and Ted Cruz have said they'd leave federal law unchanged, and continue letting states decide how to handle medical marijuana.

A Gallup poll released in October found that 58 percent of Americans support legalizing marijuana for both recreational and medical use, an all-time high, while a CBS poll from last April found that a whopping 84 percent of Americans support legalizing marijuana for solely medical use.

Obama has indicated that legalizing or rescheduling marijuana or is not on his list of priorities for 2016, but Angell said it's significant that the DEA has said it will make its decision before the president leaves office.

"This could be a legacy defining moment for him," Angell said of Obama. "If he wants to make a big move on marijuana before he leaves office, this will be the time, this will be it right here."