Washington has left some 700 combat-ready troops in Jordan following a military exercise in the country, which many believe may be used in a possible attack on Syria.
The United States has launched a multinational military drill involving Patriot missiles and fighter jets in Jordan despite condemnation from Russia.
An Afghan soldier shot dead two US troops as well as one US service member on Saturday, the latest "insider attack" to shake US-led struggle to defeat the Taliban insurgency.