This culminated in the first direct U.S. military involvement in Lebanon on December 4 .
At this time , tensions rose between Syria and the United States as Syrian anti-aircraft batteries fired on U.S. aircraft as they patrolled Lebanese airspace .
This culminated in the first direct United States military involvement in Lebanese on December 4 .
At this time , tensions rose between Syria and the United States as Syrian anti-aircraft batteries fired on U.S. aircraft as they patrolled Lebanese airspace .