I was talking to my uncle today, who was in the US Marines from 1956-1958. He said that toward the end of his enlistment his unit was packed and ready to deploy to Lebanon but it got called off at the last moment. What was going on?
Operation Blue Bat,
Famously, the somewhat overeager-for-practice U.S. forces in Blue Bat decided to re-enact D-Day on a Lebanese beach, only to find that no one in Lebanon was aware that they were in a crisis. The fully laden Marines emerging from the ocean had to pick their way through sunbathers and volleyball players as vendors kept wheeling hot dog carts up to them trying to make sales.
Simply landing a few planes of troops in Beirut and making it known that there were soldiers there would have been more than enough to stave off what turned to be very minor threats of unrest (at the time…).