The government began taking charge of airport security Monday just in time for the holiday travel season. President Bush signed legislation that will have more screeners peering in passengers' bags and more sky marshals flying on planes.

"Today we take permanent and aggressive steps to improve the security of our airways," Bush said at a ceremony at Reagan National Airport, the last major U.S. airport to re-open after the Sept. 11 attacks.

The federal government will now assume control of passenger and baggage screening operations, currently run by private security firms contracted by airlines, and put all 28,000 screeners on the federal payroll.

The signing of the most comprehensive air security bill in the nation's history came three days after passage by Congress and three days before Thanksgiving. Lawmakers and the administration were determined to act before the holidays in an effort to convince travelers that it was safe to get back on airplanes 10 weeks after the hijacker attacks on New York and Washington.

"For our airways there is one supreme priority, security. For the first time, airport security will become a direct federal responsibility," Bush said.

The new bill contains some provisions that Bush had resisted.

Bush wanted most baggage screeners to remain employees of private companies, to give airports, airlines and the government more flexibility in hiring and firing them.

For three years after the law goes into effect, all airports must be under the federal system, except for five airports of different sizes that can apply for pilot programs trying different screening approaches. After that, airports can opt out of the federal system.

The measure also moves toward 100 percent inspection of checked bags and seeks to ensure that a potential hijacker who gets into a plane will be stopped by air marshals in the cabin and reinforced cockpit doors.

Few signs of change will be evident immediately.

The government will have a year to take control of passenger and baggage screening operations and to put all 28,000 screeners on the federal payroll.

Among the more immediate effects of the new law will be a heightened law enforcement presence. The package requires at least one law enforcement officer at every screening post at major airports.

In addition, more checked bags will be inspected. Airports have 60 days to initiate plans to increase such screening, with a deadline of the end of 2002 for subjecting all checked bags to explosives detection screening.

Travelers will feel one change early next year: To pay for the beefed-up security, the measure levies a $2.50 security fee each time a passenger boards a plane, with a $5 maximum for a one-way trip with multiple legs.

The Associated Press contributed to this report.