The United Kingdom (U.K.) is reportedly considering making changes to its stringent set of entry regulations for foreign travelers and residents returning from their summertime trips beyond its borders.

While the U.K. technically reopened for international travel in mid-May, it maintains a three-tier “traffic light” system, by which it categorizes countries as “green”, “amber” or “red”, with each level carrying specific sets of progressively heightened quarantine and testing requirements.

Post-Brexit U.K. policies aren’t aligned with the European Commission’s guidelines for the European Union’s (E.U.) member nations, which have just shifted to enable quarantine-free leisure travel from the U.S. with proof of vaccination or a negative COVID-19 test.

Only a small group of foreign nations made it onto the “green” list (which carries no quarantine, but some testing, restrictions) while major destinations like Spain, France, Italy and the United States were relegated to the “amber” tier. Travel from amber countries is discouraged, and all arrivals must comply with a series of testing requirements and full 10-day quarantine upon entering the U.K.

With the summer tourism season now underway, the airline industry is desperate for a relaxation of these restrictions, which are deterring travel at the time of year that typically generates them the most revenue.

Europe’s largest airline, Ryanair, and other airlines have been railing against the Johnson administration’s travel rules, which currently make no allowances for visitors or returning nationals who are fully vaccinated. The aviation sector has repeatedly pressed the government to grant quarantine-free entry to inoculated travelers, and to ease restrictions for certain lower-risk regions, such as Malta, and the Spanish and Greek Islands.

On Thursday, Ryanair, teamed up with Manchester Airports Group (MAG) to take legal action against Britain over its “traffic light” system, and officially filed papers for judicial review with England’s High Court at around 12:00 p.m. GMT, a MAG spokesperson told Reuters . Other airlines are expected to join the action in the coming days.

In response, the U.K. Department for Transport actually indicated on Thursday that it is considering how vaccination status might play into Britain’s international travel policies moving forward. Over half of adults in the U.K. have already received both doses of an approved COVID-19 vaccine, which represents far better vaccination progress than the rest of Europe.

"We have commenced work to consider the role of vaccinations in shaping a different set of health and testing measures for inbound travel," a government spokesperson told Reuters. The Daily Telegraph reportedly wrote that the government was contemplating following the E.U.’s lead in allowing fully vaccinated foreign tourists, after all. Jesse Norman, Financial Secretary to the Treasury, today told Sky News, "We are trying to move cautiously and progressively in the right direction, so I wouldn't write anything off at this point."

On home soil, the U.K. is currently trying to contain the rapidly spreading Delta COVID-19 variant, which came from India and is responsible for a 50-percent increase in infections across England since May. This prompted Prime Minister Boris Johnson to delay his planned full reopening of the domestic economy, which had been scheduled for July 19.

Upon launching its “traffic light” system for international travel back in May, the government had promised to review its travel policy prior to the end of June and it’s set to update its list of “green” destinations on June 24.