Correction: An earlier version of this story incorrectly referred to Jordan as landlocked. The country has shoreline along the Gulf of Aqaba, which provides access to the Red Sea. The story has been updated.

Hundreds of Syrian refugees slip across the border near here each night with little more than harrowing tales and occasionally grave wounds. For this resource-poor kingdom, the newcomers are fueling new economic burdens and worries that the war next door might spread beyond its own frontiers.

Throughout much of the conflict in Syria, Jordan has hewed toward neutrality to avoid antagonizing a powerful neighbor that has long been an important trading partner and transit route for Jordanian goods. But the accelerating refugee flow and protracted war have complicated that stance, and the kingdom is raising alarm about the potential for regional instability and is increasingly siding with the Syrian regime’s opponents.

Jordan opened its first formal camp for Syrian refugees two weeks ago after more than 140,000 Syrians fleeing the conflict had already entered. The kingdom is pleading for international aid as rows of tents mushroom on a sunbaked expanse of tawny sand near this northern city.

Not far away, at a site closed to reporters, a separate camp houses deserters from Syrian security forces. Fifty miles south, in the capital of Amman, Jordan is sheltering the recently defected former Syrian prime minister — one of the starkest signs yet of Jordan’s shifting stance toward a regime with which it has maintained diplomatic relations.

The defector, Riyad Hijab, told a news conference in Amman on Tuesday that the government of Syrian President Bashar al-Assad is “collapsing” and that rebels are gaining ground.

Potential risks

Jordan’s public embrace of refugees and defectors is potentially risky for a nation that is a relative oasis of stability in a volatile region, a trait that has made it a magnet for waves of refugees from previous wars. Jordanian officials and analysts say there is rising concern about Syrian retaliation or pursuit of opposition activists inside Jordan. Officials here are also worried about internal tensions as Jordan seeks to appease a low-level protest movement calling for democratic reforms.

In recent months, Jordan’s King Abdullah II has called publicly for Assad to step down, and his government has quietly increased non-lethal assistance to opposition forces. Jordanian officials say a major concern is the possibility that Syria could fracture into tribal or ethnic enclaves. That could tug on the allegiances of tribal groups straddling Syria’s borders with Jordan, Turkey and Lebanon. It could also create openings for al-Qaeda or other terrorist organizations to dominate certain areas, they say.

In an interview broadcast last week, Abdullah described such a fracturing as a “worst-case scenario” for Jordan and raised the specter of a spread of ethnic fighting across the region, a fear Obama administration officials share.

“That means that everyone starts land-grabbing,” he told CBS News. “If Syria then implodes on itself, that would create problems that would take decades for us to come back from.”

Jordan is also worried about the fate of Syria’s arsenal of chemical weapons. Western diplomats have said that Abdullah was among the earliest backers of the recent creation of detailed contingency plans by the United States and several of its Middle Eastern allies to secure chemical arms with Special Operations troops in the event that militants seize parts of Syria.

“Today the regime has control” of its chemical weapons, Samih al-Maaytah, Jordan’s information minister, said in an interview. “The question is, after the fall, would they hand them to Hezbollah” — the Lebanese Shiite militant group — “or keep them in an Alawite country, or would they become part of the mess?”

Biggest challenge

The growing tide of Syrian refugees poses the biggest immediate challenge. There have been accounts in Jordan of border violence, and Jordanian officials say Syrian forces in several cases have shot refugees as they crossed into Jordan — including, recently, a 6-year-old boy who later died. Sometimes refugees have been shot when they were well inside Jordanian territory. Abdullah told CBS that Jordanians have occasionally fired back at the Syrians. He did not elaborate.

Jordan has had an open-door policy for Syrian refugees since they began trickling in last year. About 300 to 1,000 people now cross the border nightly, most with the help of Syrian rebels.

Trade and family ties span the frontier, and the majority have easily found shelter with relatives or friends in Jordanian cities. Syrian activists have mostly praise for Jordanian hospitality.

Until recently, Jordan appeared reluctant to open a refugee camp. But officials and analysts said the swelling population is taxing the country’s weak supplies of water, fuel and power, as well as its job market. Mounting security concerns require stricter vetting of migrants and their movements, they said.

“Since the beginning, Jordan has taken a humane role toward the refugees,” Maaytah said. “But it has been a burden economically, security-wise and politically.”

All refugees are now bused to the dusty Mafraq site, where the population is approaching 6,000. On a recent day, Andrew Harper, the Jordan representative for the United Nations refugee agency, exhorted a group of Arab diplomats who were touring the site to donate. “You can see the misery. You can see the needs,” he said.

There is the potential for “a real crisis,” said a U.S. intelligence official who has tracked the refugee flow and who spoke on the condition of anonymity to discuss sensitive intelligence reports from the region. “The country is starting to drown in refugees.”

Some analysts said that flow could provide cover for Syrian spies or armed activists, though Maaytah said Jordanian security services are confident that they can identify such actors. Omar Abdullah, a Syrian anti-regime activist in Amman, said that “smuggling weapons is a red line. They do not allow anyone to cross it.”

But stories about the presence of Syrian regime agents are circulating. In the border city of Ramtha, where cars piled with produce still rumble in each morning from Syria, Jordanian businessman Thaer al-Bashabsheh said he thinks he was a target.

His family, wealthy traders who long did business in Syria, funded and operated a prominent unofficial refugee camp in Ramtha until the official camp opened. Last month, Bashabsheh found a satellite receiver under a family car. A Jordanian bomb squad, he said, determined that it was loaded with explosives.

“We have no enemies in Jordan. The only thing we are doing is helping our brothers from Syria. So I am the enemy for Assad,” he said.

At a house in Ramtha, a Syrian schoolteacher, his wife and four children are biding their time, surviving on the charity of relatives. Two weeks ago, they escaped intense Syrian shelling in their village near the city of Daraa. Then they fled the refugee camp in Jordan, which they said was too grim.

At least the children can sleep now, said the mother, who asked to be identified by her traditional name, Um Rifaat, to avoid endangering relatives in Syria. But she said her only wish is to spend the coming Eid holiday in Syria — a Syria that is no longer led by Assad. If Syrians stay too long in Jordan, said Um Rifaat, 37, “we will become a burden.”

Warrick reported from Washington.