The Tomb of the Unknown Soldier is guarded 24 hours a day, every day of the year, and in any weather conditions. It is guarded by sentinels, who are elite members of the 3rd US Infantry Regiment. After they become qualified to guard the tomb, they are eligible to volunteer as sentinels. The 3rd US Infantry Regiment is the oldest active-duty infantry unit in the Army. It is the Army’s official unit to escort the president andto provide security for Washington, D.C., in times of emergency. Sentinels stood guard at the Tomb of the Unknown Soldier during Hurricane Sandy, even when they were advised to take shelter.