Jordan has played a critical role amid the ongoing strife in Syria that has claimed the lives of as many as 100,000, though its direct participation also comes with a cost.
Almost 2 million people have fled Syria since the civil war began in early 2011, according to U.N. numbers. By some estimates 800,000 of these poured into neighboring Jordan, a traditional safe haven for refugees from previously war-stricken regions such as Iraq and Palestine. This influx is taking a heavy toll on the Arab nation which by the end of the year may host as many as a million refugees.
Instability in Jordan creates a dangerous situation for the region.
"The one thing that could really push us into Syria is a conflict in Jordan," says Elizabeth O'Bagy, a Syria expert at the Institute for the Study of War who recently visited the area. This likely would not be in the form of ground troops, but increased aid and support for the opposition movement that is already coming largely through Jordan.
The camp at Zaatari is one of the worst for Syrian refugees due largely to inadequate resources and strict security along the border, says O'Bagy. Refugees in northern Syria have multiple countries into which they can flee, and camps in Lebanon allow refugees freer access back to their homeland.
It's not ideal, but Jordan is basically the only option for people in the south, she says. It has received much more refugees than it can possibly hold, and Zaatari is in fact now one of the largest cities in Jordan.
"Any sort of incident, I think, could very well spark underlying tensions that are already very rampant [in Jordan]," says O'Bagy.
The Islamic kingdom has historically had close ties with the U.S. and the U.K., and signed a peace treaty with Israel in 1994.
Hundreds of U.S. troops remain in Jordan, a Pentagon spokesman confirms, after first deploying there last year and swelling to the current numbers of roughly 900 following joint exercise Eager Lion. They serve in a training and advisory role for local troops, and help secure the border from the potential spillover of Syrian President Bashar al-Assad's chemical weapon stockpiles. They also have the capability to serve in a headquarters role if necessary.
Experts say the Syrian regime under Assad continually tries to "export trouble" across its border with Jordan, as it continues to combat the rebel movement at home in key cities and towns.
"For [Jordanians], this is a huge paradox," says Marc Pierini, a visiting scholar at Brussels-based Carnegie Europe and expert on Syria. "As undemocratic as it was, Syria two-and-a-half years ago was a pole of stability in the region."
The sheer numbers of refugees crossing the border is now causing serious problems for local Jordanians, whose lives are already strained by a fragile economy – Jordan is not an oil producing state – and severe droughts along the northern border with Syria.
"It's already a burden for water facilities, for health facilities, for schools and of course for the labor market," says Pierini, who served as the European Union ambassador to Syria, Libya and most recently Turkey.
The EU and U.S. have recognized the potential for disaster in recent weeks. U.S. Secretary of State John Kerry announced Tuesday he might visit a Syrian refugee camp in Jordan.
"I think we may wind up visiting one of the refugee camps as we talk about Syria," he said to a group of reporters after a meeting with Nasser Judeh, the foreign minister of Jordan, during a trip there. "We were just talking about the importance of that."