WASHINGTON, May 28 (Xinhua) -- As the United States observed the annual Memorial Day on Monday, the U.S. Army is considering new restrictions for Arlington Cemetery, the country's premier national cemetery which is running out of room.

As many as 420,000 veterans and their relatives have already found final rest places in the cemetery as about 7,000 more are added each year. At that rate, the cemetery is expected to be completely full in about 25 years, said a New York Times report on Monday.

The U.S. Army, which runs the cemetery, wants to keep Arlington going for at least another 150 years, but with no room to grow as the grounds are hemmed in by highways and development. It seems the only solution is to significantly tighten the rules for who can be buried there, said the report.

The strictest proposal the Army is considering would allow burials only for service members killed in action or awarded the military's highest decoration for heroism, the Medal of Honor. Under those restrictions, Arlington would probably conduct fewer burials in a year than it does right now in a single week.

But a policy like that would exclude thousands of currently eligible combat veterans and career officers who risked their lives in the service and who planned to be buried in Arlington among their fallen comrades. That has prompted a difficult debate over what Arlington means to the nation and how to balance egalitarian ideals against the site's physical limits.

Arlington is not the only place for military burials, of course. There are 135 national cemeteries maintained by the Department of Veterans Affairs across the country. But Arlington is by far the most prominent, and curtailing burial there would mean changing the site from an active cemetery into something closer to a museum, said the report.