FILE - In this May 20, 1995 file photo, a street sign on Pennsylvania Avenue stands above the closed section of street in front of the White House in Washington. President Bill Clinton ordered the immediate closing of Pennsylvania Avenue in front of the White House to all but pedestrian traffic, calling it "a practical step to protect against the kind of attack we saw in Oklahoma City." The Secret Service is boosting security outside the White House following an embarrassing security breach in which an intruder with a knife scaled the White House fence, dashed across the lawn and made it all the way inside before agents managed to stop him. (AP Photo/Mark Wilson, File)