Under a new policy for screening airline passengers, Transportation Security Administration officers at the airport can now require that you go through a full-body scanner even if you ask for a pat-down search instead.

The change in policy that began this month means that airline passengers can still ask TSA officers for a pat-down search instead of having to go through a full-body scanner that uses millimeter wave technology to disclose weapons hidden under clothing.

But the TSA officers now have to right to deny your request for a pat-down search “if warranted by security considerations.” If you refuse to go through the full-body scanner, the TSA can keep you from boarding your flight, according to the federal agency.

A Dec. 18 memo from the Department of Homeland Security that outlines the change in policy does not give a reason for the change.

The TSA said most passengers won’t be affected by the change. The full-body scanners that used X-rays to create what look like nude images were discontinued in 2013 after passengers complained about the potential for privacy violations and exposure to radiation.

The full-body scanners now used at all commercial airports use millimeter-wave technology to create the image of a generic avatar on a screen. If the scanner discovers a lump on the passenger that could represent a weapon, the machine shows a yellow box on the screen avatar, indicating where the lump has been spotted.

On Twitter, news of the policy sparked debate over whether the change would make air travel safer.