More than a million aviation workers — including pilots, mechanics and flight attendants — will begin undergoing more thorough background checks in January as the United States focuses on preventing insider terrorist attacks, USA Today reports.

The Transportation Security Administration (TSA) will take over the job of checking backgrounds of 1.2 million aviation workers, TSA spokeswoman Ellen Howe says. The agency will also check anyone applying for a job requiring a federal aviation license.

Since the Sept. 11 attacks, background checks have been done by the Federal Aviation Administration (FAA).

The increased scrutiny comes as the Department of Homeland Security (DHS) cracks down on the possibility of attacks by workers who don't have to go through security checkpoints to get on a plane or enter sensitive areas. USA Today reports that a former Comair airline worker was sentenced to 15 years in prison recently for sneaking guns and marijuana onto a Delta Air Lines plane in Orlando's airport in March.

The TSA takeover means every licensed aviation worker will be checked against the government's complete terror watch list, which the FBI runs, instead of a partial list the FAA has used, Howe says. The FAA licenses 21 types of workers including flight instructors, air-traffic controllers, dispatchers and flight engineers, FAA spokesman Les Dorr told USA Today.

Background checks are done automatically by a computer that compares biographical information about aviation workers to the terrorist watch list. Many airport workers, such as baggage handlers and store clerks, are not licensed but already face TSA background checks.

In addition, licensed aviation workers will be re-checked every time the Terrorist Screening Center's database is updated, which happens almost daily, Howe says. The FAA checks people only when they apply for an aviation-worker license and does not have the resources to do "perpetual vetting."

"This will raise the baseline of security," Howe says, adding that the TSA's computerized vetting system can easily handle the additional checks.

Last month, the TSA launched a program mandated by Congress that will result in background checks for more than one million port workers.

The change was welcomed by pilot groups, though they also worry that the TSA would mistake people for terrorists and prevent them from working.

"It would seem to be a logical step for the TSA," Capt. Bob Hesselbein, chairman of the Air Line Pilots Association's national security committee, told USA Today.

He added, however, that "We don't know that their processes will not misidentify people who are not a danger as a danger."