Authorities in Jordan have disrupted a major terrorist plot by al-Qaida-linked operatives to launch near-simultaneous attacks on multiple civilian and government targets, reportedly including the U.S. Embassy in the capital, Amman, Western and Middle Eastern officials said Sunday.

The Jordanian government issued a statement confirming the plot and saying that 11 people with connections to al-Qaida’s affiliate in Iraq have been arrested.

The foiled attack, described as the most serious plot uncovered in Jordan since 2005, was viewed with particular alarm by intelligence agencies because of its sophisticated design and the planned use of munitions intended for the Syria conflict — a new sign that Syria’s troubles could be spilling over into neighboring countries, the officials said.

The alleged plotters are Jordanian nationals. The officials said the group had amassed a stockpile of explosives and weapons from Syrian battlefields and devised a plan to use military-style tactics in a wave of attacks across Amman.

The scheme called for multiple strikes on shopping centers and cafes as a diversionary tactic to draw the attention of police and security officials, allowing other operatives to launch attacks against the main targets, which included government buildings and embassies.

A Western official briefed on details of the plot confirmed that the U.S. Embassy in Amman was among the targets. Like others interviewed for this report, the official spoke on the condition of anonymity because the investigation is still unfolding.

The Jordanian government’s statement said its intelligence service had broken up a cell that had been planning the attacks since June, arresting 11 people described as “supporters” of al-Qaida in Iraq.

The group had intended to use TNT and mortar shells acquired from Syria, as well as machine guns, car bombs and militia-style guerrilla tactics, to ensure “the highest death toll,” according to the statement.

A security official with ties to Jordan’s General Intelligence Directorate confirmed in an interview that the plotters were linked to al-Qaida in Iraq. He said the suspects were probably assisted by Islamist militants within Syria.

The official did not rule out involvement of the Syrian regime in the attacks but added, “We are following every lead possible.”

The timing of the plot was viewed as curious. Jordan has increasingly allied itself with forces seeking the overthrow of Syrian President Bashar al-Assad, the autocrat opposed by both rebels and a growing cadre of foreign Islamist militants inside Syria.

Jordan hosts hundreds of thousands of Syrian refugees inside its borders and has helped deliver humanitarian aid to rebel-held cities.

But intelligence gleaned from surveillance of the cell suggests that the plotters intended to destabilize Jordan’s pro-Western government with massive blows against the country’s government institutions and tourism-dependent economy, the officials said.

“This was a serious plan, with a great potential for loss of life,” said a former Western intelligence official briefed on the details.

For Jordan, which is beset by economic problems and deepening political unrest, he said, “This may not have been a tipping point, but it could have been a very hard blow.”