United States Defense Secretary Leon Panetta announced Wednesday that Washington has sent 150 troops to the Jordan-Syria border.
Defense officials said the forces in Jordan are made up of 100 military planners and other personnel who stayed on in the country after attending an annual exercise in May.
Several dozen more have flown in since, operating from a joint U.S.-Jordanian military center north of Amman that Americans have used for years.
Their mission is to help build a headquarters in Jordan and bolster its military capabilities in the event that violence escalates along the Syrian border.
Speaking at a NATO conference of defense ministers in Brussels, Panetta said Washington has been working with Jordan to monitor chemical and biological weapons sites in Syria as well as to help with the growing number of Syrian refugees.
Panetta told attendees that the United States wanted to "build a headquarters there (in Jordan) and to insure that we make the relationship between the United States and Jordan a strong one, so that we can deal with all of the possible consequences of what's happening in Syria."
The announcement came as Washington continues to deny military involvement in the conflict. It follows several days of shelling between Turkey and Syria -- an indication that the civil war could become a regional conflict.
The Obama administration has warned that the United States will change its policy of providing only non-lethal aid to the rebels if the Syrian government uses chemical weapons.