Federal officials say they might well shut down the Gateway Arch if a war with Iraq increases security threats. The Arch is one of five popular tourist sites in the United States that are potential targets for terrorist attack, says the National Parks Service. Parks Service spokesman Dave Barna says the five represent international symbols of the United States and that people overseas know where they are. Along with the Arch, the other high profile sites include the Statue of Liberty, the Washington Monument, the White House, and the Liberty Bell pavilion in Philadelphia. An Interior Department spokesman says the tourist attractions would likely be sealed off under an increased security threat. The Gateway Arch in St. Louis attracts about 4-Million visitors a year.