The heavily fenced Syria-Israel border crossing on Wednesday - little sign here that a cross border attack may have taken place.<br/> <br />But now security sources and a Western diplomat say that's what happened somewhere on the Syrian border with neighbouring Lebanon.<br/> <br />One security source said there was definitely a hit in the border area, while the diplomat said "something has happened" without elaborating, leaving the events -- at least for now -- shrouded in mystery.<br/> <br />The Lebanese army reported a heavy presence of Israeli jet over its territory throughout the night.<br/> <br />Israelis are on alert for any potential attack from Syria or Lebanon following a series of government warnings - some are here on Wednesday collecting gas masks.<br/> <br />Israel's Vice Premier Silvan Shalom said on Sunday that any sign that Syria's grip on its chemical weapons was slipping could trigger Israeli intervention.<br/> <br />Israeli sources said on Tuesday, though, that Syria's advanced conventional weapons would represent as much of a threat to the Jewish state as its chemical arms should they fall into the hands of Syrian rebel forces, or Hezbollah guerillas based in Lebanon.<br/> <br />Lebanon frequently complains that Israeli jets overfly its territory.<br/> <br />However the recent activity was reported to be much more concentrated than usual.
