Attorney General Merrick Garland issued a memo Wednesday directing federal prosecutors to prioritize investigations into crimes committed on planes, as record numbers of unruly passengers continue to disrupt travel.

“Passengers who assault, intimidate or threaten violence against flight crews and flight attendants do more than harm those employees; they prevent the performance of critical duties that help ensure safe air travel,” Garland said.

“Similarly, when passengers commit violent acts against other passengers in the close confines of a commercial aircraft, the conduct endangers everyone aboard,” he said.

The Federal Aviation Administration has been using its civil authorities to try to crack down on misbehaving passengers, opening 266 enforcement cases, and has sought federal criminal investigations in 37 cases. The majority of incidents have stemmed from disputes over wearing masks, which is required throughout the aviation system.

While federal authorities have said they have zero tolerance for bad behavior on planes, the sheer number of incidents this year has strained the systems designed to provide for accountability. Responsibility of investigating cases is shared among several agencies, including local police.

Garland’s memo could help bring more resources to bear on the problem and streamline investigations. He directed federal prosecutors to communicate to local authorities that crimes on planes were a priority for the Justice Department.

The memo comes as millions of Americans fly this week to attend Thanksgiving celebrations, pushing passenger numbers to their highest levels since the beginning of the pandemic. Garland told his staff that by focusing on crimes on board planes they were “helping to ensure that people across the country can travel safely this holiday season and beyond.”

FAA Administrator Stephen Dickson said he valued his agency’s partnership with the Justice Department.

“The unacceptable disruptive behavior that we’re seeing is a serious safety threat to flights, and we’re committed to our partnership with the DOJ to combat it,” he said in a statement.

In all, the FAA has received 5,338 reports of unruly passengers this year and has launched 1,012 investigations.

On Monday, the agency announced fines totaling nearly $162,000 in connection with eight incidents involving drunk passengers. In one April incident, the FAA alleged that a passenger drank their own alcohol — a violation of federal rules — smoked marijuana and sexually assaulted a flight attendant. And in a March incident, a flight bound for Detroit was diverted to Atlanta after a passenger the FAA said was drunk wouldn’t keep his mask on and swore at other travelers.

The federal mask mandate for transportation remains in effect until Jan. 18. On Wednesday, the leaders of the House Homeland Security Committee said the Transportation Security Administration had been stepping up its enforcement of the mandate, issuing 2,310 warnings and 199 penalty notices.

“TSA needs to continue to increase enforcement to ensure violators face consequences,” Reps. Bennie G. Thompson (D-Miss) and Bonnie Watson Coleman (D-N.J.) said in a statement. “These actions are critical to hold offenders accountable, discourage unacceptable behavior, and deter potential threats that put both travelers and the frontline TSA workforce at risk.”