WASHINGTON, March 19 (IslamOnline & News Agencies) - The Pentagon said Monday, March 18, that it is preparing to scale back combat air patrols over U.S. cities in a reflection of improved security at airports and aboard airliners.

They will now rely on intermittent patrols with a plan to keep fighter jets on "strip alert," ready to fly within 15 minutes, officials said.

"We're talking about a different mix, and it will probably be somewhat less than you have had in the past," said Victoria Clarke, the Pentagon spokeswoman.

The military put U.S. fighter aircraft on combat patrols over New York, Washington and other U.S. cities after terrorists flew hijacked jetliners into the World Trade Center in New York and the Pentagon on September 11.

But military commanders have complained that the patrols have strained the force and cut into training time.

Clarke said airport and airliner security have improved, and people were much attuned to the threat.

Improved security measures include more federal marshals on commercial flights, stronger cockpit doors on jetliners, more stringent security at airports and an instant alert system between the Federal Aviation Administration and the North American Aerospace Defense Command, which orders military aircraft into the sky, reports CNN.

U.S. President George W. Bush has been briefed on the Pentagon's plan to change the mix of its combat air patrols and strip alerts to "more accurately reflect the current environment."

"You'll have some combination of CAPs [combat air patrols], strip alerts and the combination will change as circumstances demand," she said.