AMMAN -- The United States has been slowly building a small military contingent on the Syrian border in Jordan as conflict rages in Syria. 

The fighting in Syria has increasingly dragged in regional and international powers, even if - as in the case of the United States - the engagement appears reluctant.

The U.S. has plans to boost its small presence in neighboring Jordan, begun last year, to some 200 personnel - to prepare for a variety of scenarios, including a spillover of violence or the need to secure chemical weapons.

U.S. Defense Secretary Chuck Hagel says military intervention “is always an option” but in the case of Syria, "an option of last resort."

Such assurances have not calmed the fears of all Jordanians, says journalist Assil Mezher.

"We all know that when countries move troops into other countries that means a war is coming on the way," said Mezher.

Jordan is already deeply affected by the conflict, now in its third year, taking in nearly half a million Syrian refugees and straining its limited resources.  It has also been pulled by an uncomfortable web of alliances, including pro-opposition "Friends of Syria," the Syrian government's supporters in Iran, and its cold-peace ally, Israel.

Jordan has outwardly tried to stay neutral in the conflict, but hosting U.S. forces places it more firmly with the Syrian opposition.

Some in Jordan welcome that move, but insist the U.S. must not intervene directly on the rebels' side, says analyst Salem al Falahat.

"This is condemned by the Arab nations and this causes harm to the Syrian revolution," said al Falahat.

The U.S. has made clear it understands the complexities involved and the risk of unintended consequences that intervention could cause.

But some in Jordan were rattled  when The Los Angeles Times last month quoted senior U.S. officials as saying up to 20,000 U.S. troops could be deployed, says analyst Fayez al Dwairi.

"The American position is not clear and not stable with regards to the Syrian crisis," said al Dwairi.

But as the U.S. draws down after a decade of military intervention in the region, even analysts unsure of American intentions say they believe the U.S. presence is likely to remain limited for now.