LONDON — The U.K. government has opened the door to new green taxes on airline passengers, just five months after playing down the idea.

If the aviation sector “is not meeting the emissions reductions trajectory” required to bring down pollution, ministers will “consider what further measures may be needed to ensure that the sector maximizes in-sector reductions to meet the U.K.’s overall 2050 net zero target,” the government told MPs in a letter Wednesday.

The U-turn came in response to Parliament’s Environmental Audit Committee (EAC) recommendations in December that the government prepares policies to bring down carbon emissions in the aviation sector, including “a frequent flyer levy.”

Transport Minister Anthony Browne told POLITICO last November that cutting flight demand is not the answer to reaching net zero. He said innovation in the aviation sector should come before behavioral change and demand reduction.

The government, he said, is “not in the business of telling people not to fly.”

“Even if people fly a bit less, the planes — if they still use normal aviation fuel — will still contribute huge amounts of carbon dioxide,” he added.

The EAC urged the government to keep their options open for reducing demand, such as by slashing rail fare prices.

EAC member and Conservative MP Jerome Mayhew said: “If a future review of the Jet Zero Strategy — which the committee recommended takes place by 2025 — reveals that sufficient progress is not being made, the government must not be afraid to alter course mid-flight to maintain progress towards our net zero goals.”