In response to these and other incidents, the White House gates
have been strengthened, and electronic detection devices have
been installed at the edge of the grounds to detect intntders. In
addition, Secret Service officers are stationed on the White
House roof to watch for intrusions by aircraft.
Staff writers Marcia Davis, Hamil R. Harrls, Vernon Loeb, Steve
Vogel and Linda Wheeler contributed to this report.
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