The ban on electronics larger than a cellphone on incoming flights to the United States and the United Kingdom from a handful of airports in the Middle East and North Africa was announced Tuesday without much information to back it up.

But the action was probably based on credible terrorist threats against air travel, experts said.

The link between terror and aviation isn’t new, and the fact that other countries are implementing versions of an electronics ban points to the legitimacy of the threats. Still, the rollout of the ban in the U.S. lacked transparency and will likely cause confusion and apprehension on the part of many travelers.

The Department of Homeland Security released a fact sheet on Tuesday that leaves unanswered many questions about the ban ― like why laptops or tablets are any more dangerous than cellphones. Sean Spicer, the White House press secretary, didn’t bother answering any of the lingering questions, either.

“As you can imagine, I can’t talk about the intelligence we have,” Spicer said during Tuesday’s news briefing. “I can just tell you that the steps we are taking are commensurate with the intelligence we have.”

Wolfgang Rattay / Reuters Some airports, like Istanbul's Ataturk airport, require several security screenings before boarding the plane.

Experts agreed there’s probably a tangible threat, most likely emanating from al Qaeda in the Arabian Peninsula, which has a history of targeting aviation.

“There’s been repeated AQAP and Islamic State attempts to build explosives into electronic devices,” said Clinton Watts, a fellow at the Foreign Policy Research Institute. The threats date to a foiled 2009 plot to fill a printer cartridge with explosives.

Enhanced aviation security measures were put in place three or four times during the Obama administration, said Christian Beckner, deputy director of George Washington University’s Center for Cyber and Homeland Security. “At this point, this looks more to me like something that’s generally consistent with prior action that’s been taken,” he said of Tuesday’s order.

If the AQAP threat has loomed over the U.S. for years, it raises the question of why the ban is just now going into effect. Either there is credible intelligence of a threat coming from countries the ban affects, or the administration believes “security is weak in those parts,” Watts said.

But security at many of the affected airports, like those in Doha and Dubai, is on par with or better than in the U.S. That means the explanation probably is new intelligence or a threat, Watts said.

“Now is the best time in a long time to launch an international terrorist attack just because America will be forced by the administration to respond hard,” he said.

2- DHS laptop ban - does this just point to which countries the US believes have inadequate airport security screening procedures? — Clint Watts (@selectedwisdom) March 21, 2017

The U.K. government imposed its own ban following the U.S. action on Tuesday. Canada also is considering one. Moves by multiple countries lend credence to the threats, Beckner and Watts said.

“I think it confirms that it’s less like the travel executive orders and more consistent with the longstanding way we’ve treated impending urgent information on aviation threats,” Beckner said.

“If other countries go along with it, to me it suggests that there’s something to it,” Watts added.

Rep. Adam Schiff (D-Calif.), the House Intelligence Committee’s ranking Democrat, supported the ban after receiving an updated intelligence briefing over the weekend.

“These steps are both necessary and proportional to the threat,” Schiff said in a statement Tuesday. “The global aviation system remains a top target.”