AMMAN, Jordan (AP) -- Jordan tightened security along its border with Syria, doubling the number of soldiers as President Bashar Assad's regime warned Thursday the kingdom is "playing with fire" by allowing the U.S and other countries to train and arm Syrian rebels on its territory.
The warning, coinciding with significant rebel advances near the border, plays into Jordanian fears that its larger neighbor might try to retaliate for its support of the opposition fighters.
The stepped up security also reflects the kingdom's fears that the chaos from Syria's 2-year-old civil war could lead to a failed state on its doorstep where Islamic militants have a free hand.
The Syrian warnings followed statements from U.S. and other Western and Arab officials that Jordan has been facilitating arms shipments and hosting training camps for Syrian rebels since last October.
A front-page editorial in the government daily al-Thawra accused Amman of adopting a policy of "ambiguity" by training the rebels while at the same time publicly insisting on a political solution to the Syrian crisis.
Jordan is "playing with fire," state radio said.
"Jordan's attempt to put out the flame from the leaked information will not help as it continues with its mysterious policy, which brings it closer to the volcanic crater," al-Thawra said.
Over the years, Syria has accused Jordan of being America's "puppet" because of its strong alliance with the United States and a "spy" for Israel, with which Amman maintains cordial ties under a peace treaty signed in 1994.
A Jordanian security official said the kingdom had tightened security along its 230-mile (370-kilometer) border with Syria, including doubling the number of soldiers in the last two days, though he declined to disclose the size of the force.
He said Jordan was also hoping to receive one or two Patriot missile batteries, which the U.S. might temporarily pull out of the Persian Gulf to station on Jordan's northern border. He spoke on condition of anonymity because he was not authorized to give official statements to the media.
Jordan's chief of staff, Gen. Mishaal Zaben, said Jordan was installing more cameras, radar and sophisticated early detection equipment to help prevent smuggling and infiltrations across the border and assist Syrian refugees as they cross into Jordan. The equipment will "significantly bolster Jordan's defenses along the border with Syria," he said.
Still, Jordanian Information Minister Sameeh Maaytah said the political tension with Syria would not evolve into an all-out war.
"Syria must be aware that Jordan has no desire to meddle in its internal affairs whether by training rebel forces, or facilitating arms shipments to them," he added. "But Jordan must protect its interests, land, border and people."
The rebels being trained in Jordan are mainly secular Sunni Muslim tribesmen from central and southern Syria who once served in the army and police. The force is expected to fill a security vacuum by protecting the border with Jordan, assisting displaced Syrians and setting up a safe haven for refugees.
They are also envisioned as a counterbalance to the Islamic militant groups that have proven to be among the most effective of the myriad rebel factions fighting Assad's forces on the ground.
Chief among these is Jabhat al-Nusra or the Nusra Front, which the U.S. designates as a terrorist group and says is associated with al-Qaida.
"Jordan can't sit idle and watch al-Qaida and other militants seizing control of its common border with Syria," Maaytah said. "It must take proactive steps to arrive at a state of equilibrium in the security structure on the border."
Jordan has also long feared that the Assad regime could use chemical weapons against it, or that agents linked to the regime or its allied Lebanese militant group Hezbollah could attack the kingdom.
Israel and the United States also are concerned about militants potentially operating in the area near the Israeli frontier with Syria in the Golan Heights should Assad's regime collapse.
Though Jordan is supporting one segment of the disparate patchwork of rebel groups, it is concerned about the recent rebel advances in the south along its border.
One fear is that the fall of the area into rebel hands could unleash lawlessness on the border and provide a haven for Islamic extremist groups such as Nusra Front.
The Islamic militants, particularly Nusra, are complicating the battlefield by thwarting much-needed international aid from countries such as the U.S. that do not want to bolster extremist jihadi groups.
Activists reported more advances in the south on Thursday.