At least two American security agents were killed during a shooting at a US-run military training complex just outside the Jordanian capital of Amman on Monday. One South African and three Jordanians were also killed, and six more persons, including two more US personnel, were wounded in the attack. The assailant was subsequently killed during a firefight with Jordanian security forces.

The shootings took place at the International Police Training Center, a facility built in the immediate wake of the 2003 US invasion of Iraq, along with several other US military bases, and designed to train new Iraqi security forces. The center is effectively run by the US State Department, which provides the training programs and instructors.

The center trains security agents for police operations in Libya, Iraq and Palestine, according to the Washington Post. Training programs at the Jordanian school are designed by US officers and overseen by a team of “senior police and security advisors,” according to the Wall Street Journal.

The attack was carried out by 28-year-old Jordanian police captain Anwar Abu Zaid, according to media reports. Zaid is a relative of Jordanian parliamentary deputy Suleiman Saed, according to an MP cited by the Lebanese Daily Star.

Zaid served as “a senior Jordanian co-trainer with a captain’s rank at the US-funded center,” according to al Bawaba. The Jordanian policeman was married with two young children. He wore a military uniform during the incident.

The incident was the most significant attack against a Jordanian security base to occur in more than three decades, a former Jordanian military officer told the Associated Press.

The US is treating the incident “very seriously,” President Barack Obama said in comments Monday during a meeting with Israeli Prime Minister Benjamin Netanyahu at the White House.

“We’ll be working very closely with the Jordanians to determine exactly what happened,” Obama said, vowing a “full investigation.”

The incident occurred exactly 10 years to the day after a series of bombings of hotels in Amman killed some 60 people. Responsibility for those bombings was claimed by Al Qaeda in Iraq, a precursor organization to Islamic State in Iraq and Syria (ISIS).

Pointing on this overlap, Jordanian officials have made vague accusations against “Islamist terrorism” in the wake of the attack. “This incident sadly does not come as a surprise as the threat of Islamist terrorism has only increased in the region in the last few years in the aftermath of Syria and Iraq,” an unnamed senior Jordanian official told US media.

The US victims were employees of DynCorp, a private military firm based in northern Virginia, according to the US State Department. DynCorp employs many former government agents, both military and diplomatic. The security contractors were training Iraqi and Palestinian security forces at the time of the attack, according to Reuters.

The US currently maintains some 1,000 military and police trainers inside Jordan, including private contractors and government personnel. Jordan is a key US regional ally, “at the top of our list of foreign partners,” as described by one former CIA agent quoted in the Los Angeles Times.

In a show of solidarity, Jordanian King Abdullah II visited wounded victims of unidentified nationality on Monday.

Jordan’s elite commando units, frequently touted by the regime as the best soldiers in the Middle East, were created with close support from the US military. In 2009, the US built a new, massive commando training facility in the Jordanian desert, one of the largest such facilities in the world, known as the King Abdullah Special Operations Training Center.

Speculation is rampant over possible political motivations for the attack. There is no shortage of possible motivations behind the incident. The facility in question is located near one of the main epicenters of US covert operations worldwide, and was staffed by veteran US security cadres.

While US efforts to train a new Syrian rebel army have floundered during the past year, failing to train more than a handful of new US proxy forces, this was only the latest US covert operation run out of the country.

US bases in Jordan have been instrumental in organizing the US military-intelligence operations which fomented the violent insurgency against the Syrian government that erupted in 2011. The ongoing US air war in Syria also relies heavily on Jordanian bases. These operations have already led to the deaths of hundreds of thousands of civilians and have produced a still-escalating proxy war involving the US, Russia, Iran and the European powers that is destabilizing the entire region.

“CIA money goes toward running secret training camps in Jordan, gathering intelligence to help guide the operations of agency-backed militias and managing a sprawling logistics network used to move fighters, ammunition and weapons into the country,” a Washington Post report on the CIA programs, which had already trained some 10,000 mercenaries for the war in Syria at the time, noted.

The CIA programs were running an annual budget of over $1 billion per year as of June 2015, as part of a “broader, multibillion-dollar effort involving Saudi Arabia, Qatar and Turkey.”

CIA paramilitary teams and US Special Forces commandos have been training Syrian “rebels” in the use of anti-aircraft and anti-armor missiles since at least 2012, at least one year before the Obama administration publicly acknowledged the training programs.

Fresh detachments of US special forces teams deployed to Jordan in 2014 for joint training with Jordanian and Iraqi “counter terror” units, according to “American Covert Operations: A Guide to the Issues.”

Historically, the Jordanian government has enjoyed intimate relations with sections of the American state for years and decades prior to the Syrian war. As early as 2005, the Jordanian General Intelligence Directorate (GID) had “surpassed Israel’s Mossad as America’s most effective allied counter-terrorism agency in the Middle East,” according to the Los Angeles Times.

Jordan’s GID has benefited from extensive secret financial aid from Washington and hosts a permanent CIA presence at its central offices. “The two intelligence agencies [GID and CIA] conduct sophisticated joint operations and routinely share information,” the Times noted.

“We have had some ups and downs in our public bilateral relationship with Jordan. The one constant has been the close ties between the CIA and the king and his government,” a retired US Middle East analyst told the newspaper.

Jordan has also been a central collaborator with the US global torture network, lending various forms of support to the CIA’s “extraordinary rendition” missions. Jordanian intelligence regularly engages in torture of detainees, according to the US State Department’s own human rights reporting, yet this has not stopped the US from repeatedly handing over prisoners to the GID.