BALTIMORE -- United Airlines becomes the fourth airline to join "Operation Hero Miles," an initiative to support domestic travel for U.S. soldiers on leave under the Operation Iraqi Freedom Rest and Relaxation program.

MORE INFORMATION To donate your air miles, log on to the congressman's Web site

Saying some soldiers -- particularly those from the West Coast -- spend more than $1,000 to get home on the military's R&R program, Rep. Dutch Ruppersberger, D-District 2, established the initiative.

In October, the Pentagon started giving soldiers two-week leaves in the largest R&R program since the Vietnam War. Some flew to Germany and others to Baltimore-Washington International Airport for free. The soldiers are responsible for flights the rest of the way to their destination, although major airlines have offered discounts.

Ruppersberger asked airlines to help set up a pool through which frequent fliers can donate miles for use by vacationing soldiers. Delta Air Lines was the first airline to announce it would participate, followed by Southwest and Alaska airlines.

According to the congressman's office, United donated 10 million miles and will match up to 5 million miles through their "Mileage Plus" program.

The soldiers granted leave fly into the country via Baltimore-Washington International Airport in addition to airports in Atlanta and Dallas. From these airports, the soldiers pay their way on flights back to their hometowns.

To donate your frequent flier miles, the congressman asks that you log on to the initiative's Web site.

United customers can also donate their miles, at a 1,000-mile minimum, by calling the customer service center by dialing (800) 421-4655.

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