The U.S. Army Corps of Engineers plans to supervise construction of a five-story underground facility for an Israel Defense Forces complex, oddly named Site 911," at an Israeli Air Force base near Tel Aviv. Only U.S. construction firms are being allowed to bid on the contract and proposals are due Dec. 3, according to the latest Corps of Engineers notice. Site 911 is the latest in a long history of military construction projects the United States has undertaken for the IDF under the U.S. Foreign Military Sales program. The 1998 Wye River Memorandum between Israel and the Palestinian Authority has led to about $500 million in U.S. construction of military facilities for the Israelis, most of them initially in an undeveloped part of the Negev Desert. Over the years, the Corps has built underground hangers for Israeli fighter-bombers, facilities for handling nuclear weapons (though Israel does not admit having such weapons), command centers, training bases, intelligence facilities and simulators. Site 911 ... appears to be one of the largest projects. Each of the first three underground floors is to be roughly 41,000 square feet, according to the Corps notice. The lower two floors are much smaller and hold equipment. The purpose of Site 911 is far less clear.