Why on earth war-torn Syria would even consider invading Jordan is unclear, but the US troops on the ground in Jordan are apparently spending all their time preparing for that eventuality anyhow, at least according to Jordanian officials familiar with the situation.
The 150 US troops are deployed in a base on the outskirts of Amman, and have apparently been spending time on the dual goals of reinforcing the Jordanian side of the border with Syria, and preparing for the possibility of a chemical weapons attack.
Which seems enormously unlikely, as Syria has repeatedly said that they will only use their chemical weapon arsenal in retaliation for a foreign invasion. The more plausible explanation is the one raised when the US deployment was first revealed, that the troops are actually planning for a raid into Syria to seize the nation’s chemical weapons.
Though there has been some spillover of the Syrian Civil War into Jordan, most of the fighting now is centering on the northern frontier of Syria, along the border with Turkey.