Speaking at a NATO conference of defence ministers in Brussels, Panetta said the US has been working with Jordan to monitor chemical and biological weapons sites in Syria and also to help Jordan deal with refugees pouring over the border from Syria.
But the revelation of US military personnel so close to the 19-month-old Syrian conflict suggests an escalation in the US military involvement in the conflict, even as Washington pushes back on any suggestion of a direct intervention in Syria.
It also follows several days of shelling between Turkey and Syria, an indication that the civil war could spill across Syria's borders and become a regional conflict.
"We have a group of our forces there working to help build a headquarters there and to ensure that we make the relationship between the United States and Jordan a strong one so that we can deal with all the possible consequences of what's happening in Syria," Panetta said.
The development comes with the US presidential election less than a month away, and at a time when Mitt Romney, the Republican nominee, has been criticising President Barack Obama's foreign policy, accusing the administration of embracing too passive a stance in the convulsive Mideast region.
The defence secretary and other administration officials have expressed concern about Syrian President Bashar Assad's arsenal of chemical weapons.
Panetta said last week that the United States believes that while the weapons are still secure, intelligence suggests the regime might have moved the weapons to protect them.
The Obama administration has said that Assad's use of chemical weapons would be a "red line" that would change the U.S. Policy of providing only non-lethal aid to the rebels seeking to topple him.
Pentagon press secretary George Little, travelling with Panetta, said the US and Jordan agreed that "increased cooperation and more detailed planning are necessary in order to respond to the severe consequences of the Assad regime's brutality."
He said the US has provided medical kits, water tanks, and other forms of humanitarian aid to help Jordanians assist Syrian refugees fleeing into their country.
Brussels: The United States has sent military troops to the Jordan-Syria border to help build a headquarters in Jordan and bolster that country's military capabilities in the event that violence escalates along its border with Syria, Defence Secretary Leon Panetta said Wednesday.
First Published: Wednesday, October 10, 2012, 22:22