Europe is bracing for major turbulence: An electronics ban on flights to America.

European airlines and regulators are preparing for the possibility that the Trump administration could ban laptops and other large devices from the cabins of flights from Europe to the United States.

Such a move would represent a massive expansion of a laptop ban imposed in March on airlines flying out of 10 airports in the Middle East and Africa. Passengers on those flights are now required to carry anything bigger than a smartphone in checked baggage.

In the United States, a Capitol Hill source and a Homeland Security source told CNN on Thursday that it was increasingly likely the ban would be expanded soon. Homeland Security Secretary John Kelly met with lawmakers to discuss aviation security.

The sources stressed that no final decision had been made.

A senior European transport official said the aviation industry was expecting the U.S. to extend the ban to Europe, and described the situation as "a total mess."

"We're expecting something to happen, we're just not sure exactly what or when," said a senior executive at a major European airline.

The controversial security measures have been criticized by Middle Eastern airlines and other aviation experts, who have questioned the rationale for the policy, complained about the impact on their business, and warned of safety risks associated with carrying large numbers of lithium batteries in the cargo hold of aircraft.

A Capitol Hill source said it would be difficult to institute the ban in Europe without expanding it to flights leaving the United States. European airport security measures are closely aligned with American measures, and U.S. aviation security has had its own failures.

But a U.S. official disagreed with that assessment.

"The reason we are not looking at expanding the ban to flights leaving the U.S. is because the intel does not suggest that's necessary," the official said. "The intelligence is pointing to something else beyond that. This is not an indictment on Europe's security measures. We are acting on specific intelligence."

Extending the restrictions to Europe would have a much larger impact on the industry than the ban in the Middle East.

Roughly 40% of overseas travelers to the U.S. come from Europe, crossing the Atlantic on more than 350 flights a day.

Many of the flights are operated by U.S. airlines such as Delta (DAL), United (UAL) and American (AAL), or their European partners.

Related: U.S. laptop ban could hit 350 flights a day from Europe

The specifics of the restrictions under consideration are not yet clear.

Department of Homeland Security officials spoke with airline industry representatives about the electronics ban on Thursday, according to Homeland Security and industry sources.

Homeland Security said in a statement Wednesday that the restriction was under consideration.

U.S. airlines have been pushing Homeland Security to find less disruptive alternatives, according to a source familiar with the discussions. One possible alternative could be additional screening at boarding gates, but "the logistics are very complicated," the source added.

Related: Emirates president says it's 'amazing' to suggest Dubai airport is not safe

Alarm bells are already ringing in Europe, however.

Some airline stocks were lower on Thursday. Lufthansa (DLAKY) shares declined 2%, while British Airways parent IAG shed 1.7%. United Airlines shares were trading down 1% in New York.

Anna-Kaisa Itkonen, a spokeswoman for the European Commission, said that European officials had sent a letter on Tuesday to their American counterparts.

The officials had asked that the U.S. and Europe continue to cooperate on a "joint response to shared threats."

"The Commission is keen to work closely with all international partners -- including the U.S. authorities -- on identifying developing threats in aviation and the best ways to address them together," Itkonen said.

The Trump administration has said the original ban was necessary because intelligence suggests terrorists are now able to hide explosives in laptops and other devices.

But that argument hasn't won over the industry. The head of the International Air Transport Association, Alexandre de Juniac, told CNNMoney in March that it wasn't an appropriate solution to the threat, would hurt the airlines affected, and should be overturned. In March, the U.K. also banned electronics on some flights from the Middle East.

Related: European regulator flags safety risk of laptop ban

Europe's aviation safety agency has issued a warning about the risks of carrying laptops and other devices in checked baggage. It said that carrying a large number of lithium batteries in the cargo compartment increases the risk of an accidental fire.

--CNNMoney's Alanna Petroff and Richard Quest contributed to this report.