Attorney General Jeff Sessions says he wants to have a “continuing dialogue” with Colorado Gov. John Hicklenlooper about marijuana legalization in the state, and said one report raises “serious concerns.”

Sessions sent a letter to Hickenlooper dated July 24 laying out some of the findings from a 2016 report by the Rocky Mountain High Intensity Drug Trafficking area that claims marijuana originating from Colorado has been distributed to other states, the number of traffic deaths related to pot has increased 48 percent and that youth pot usage is up 20 percent.

In the letter, Sessions said the report “raises serious questions about the efficacy of marijuana ‘regulatory structures’ in Colorado.”

The letter closes with Sessions asking Colorado to weigh in on what they’re doing to counteract some of the impacts of legal marijuana the report found:

“These findings are relevant to the policy debate concerning marijuana legalization. I appreciate your offer to engage in a continuing dialogue on this important issue. To that end, please advise as to how Colorado plans to address the serious findings in the Rocky Mountain HIDTA report, including efforts to ensure that all marijuana activity is compliant with state marijuana laws, to combat diversion of marijuana, to protect public health and safety, and to prevent marijuana use by minors. I also am open to suggestions on marijuana policy and related matters as we work to carry out our duties to effectively and faithfully execute the laws of the United States.”

Sessions also discusses the Cole Memorandum, an Obama era series of guidelines about how states and the federal government would approach pot legalization.

You can read a full version of Sessions’ letter below:

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