Nine months after US airports allowed passengers to pass through scanners without taking off their shoes, rescinding the stringent policy after almost two decades, a top senator claimed the “reckless” move could put passengers in danger.

The policy amounts to a “potentially catastrophic security deficiency”, according to Tammy Duckworth, Democrat for Illinois, and ranking member of the Senate commerce, science and transportation (CST) aviation subcommittee.

In a letter to Ha Nguyen McNeill, deputy administrator of the Transportation Security Administration (TSA), Duckworth cited news reports that some scanners can’t scan shoes.

The new shoes-on policy was introduced by the former Department of Homeland Security (DHS) secretary, Kristi Noem, last July, ending a rule that came into effect after “shoe bomber” Richard Reid’s failed attempt to take down a flight from Paris to Miami in December 2001 with explosives in his shoes.

He was later sentenced to three life terms plus 110 years in prison.

Duckworth, who lost both legs and partial use of her right arm in 2004 when her Black Hawk helicopter was hit by an RPG during the second Iraq war, said in a statement that Noem’s decision was a “reckless act” that was “likely without meaningful consultation with TSA”.

The TSA and DHS did not immediately respond to requests for comment.

Noem also mulled relaxing restrictions on the volume of liquids airline passengers are allowed to bring on flights as hand-luggage. Most remain in place, but medically necessary liquids, gels, and aerosols in quantities greater than 3.4 ounces are now allowed if they are first declared.

Duckworth recently re-introduced a bill making it easier for parents to travel through airports with breast milk and breastfeeding supplies after some were found to be dumping the supplies before passing security.

In a statement on Friday, Duckworth said the DHS inspector general conducted covert testing that reportedly found some TSA full body scanners “can’t scan shoes”, adding that the office of inspector general had determined that the policy move “inadvertently created a new security vulnerability in the system”.

“At a minimum, TSA’s failure to swiftly implement corrective action warrants the immediate withdrawal of Secretary Noem’s reckless and dangerous policy that increases the risk of a terrorist smuggling a dangerous item onto a flight,” the senator wrote in her letter to TSA.

The demand to reinstate the shoe policy comes as US travelers face long lines to clear security at airports after a record-long partial government shutdown. Hundreds of TSA workers have left the agency since the shutdown began, though missed paychecks have been paid retroactively.