Israel is reportedly receiving some assistance in retrieving hostages from the United States, although in what form that comes beyond “advise and assist” is not yet clear.
2,400 U.S. Marines of the 26th Expeditionary Unit have been withdrawn from exercises in Kuwait and are on standby to engage with “emerging events” if required, but whether this means Israel has not been confirmed.
The Corps is an expeditionary force that is readily deployed around the globe at all times. They were likely on a float and stopped in for some dessert drills. The Army and National Guard units should be on the border, but not the Marines.