Montgomery, AL – December 23rd is one of the year's busier travel days. At least 30 Alabama National Guard troops are providing extra security at Alabama's major airports in Huntsville, Birmingham, Montgomery and Mobile. Experts say those traveling by plane should allow a couple of hours to get through security lines at airports. There are no known terrorist threats against targets in Alabama, but state security officials are urging residents and travelers to be alert. The nation has been under a high terror alert since the weekend. Governor Bob Riley says Alabamians should go about their regular business but keep their eyes and ears open.