Saudi Arabia has deployed 100,000 security personnel to oversee the annual Islamic hajj pilgrimage that begins on Tuesday, the Interior Ministry spokesman said, underscoring both the massive arrangements needed to secure one of the largest pilgrimages in the world and the multitude of threats the hajj faces.

"We always concentrate on hajj considering that a threat might exist," Maj. Gen. Mansour al-Turki said. "We've been targeted by terrorism for years now and we know that we are a target for terrorist groups."

Al-Turki spoke exclusively to The Associated Press on Saturday from the Interior Ministry's security headquarters for the hajj, located in the sprawling tent city of Mina just a few miles outside the Grand Mosque in Mecca that houses Islam's holiest site, the cube-shaped Kaaba.

Roughly 3 million people from around the world are expected to converge at the Kaaba, in Mina and other nearby areas for the hajj, which lasts about five days. It is series of rituals meant to cleanse the soul of sins and instill a sense of equality and brotherhood. All able-bodied Muslims are required to perform the hajj once in their lives.

Members of an elite counterterrorism unit, traffic police and emergency civil defense personnel are among those deployed to help with crowd control and safety. They are supported by additional troops from the army and national guard, al-Turki said.

Inside the Interior Ministry's nerve center, police monitor dozens of screens with feeds from about 5,000 CCTV cameras installed throughout Mecca and Medina, the two cities frequented by pilgrims.

"We're active, we're awake," al-Turki said, referring to the security forces' readiness to deal with any eventuality.

Civil defense emergency personnel were among the first responders when a crane collapsed at the Grand Mosque on Sept. 11, killing 111 people and injuring nearly 400 others who had come for the hajj. Authorities blamed the collapse on high winds and the contractor was faulted for not following operating procedures.

On Thursday, the kingdom's military and police put on a parade in Mecca, with security forces jumping through burning hoops and thwarting a mock terrorist attack. The show was aimed at deterring any would-be troublemakers, and was attended by Crown Prince and Interior Minister Mohammed bin Nayef, who himself was the target of a terrorist attack in 2009.

Saudi Arabia's custodianship of holy sites in Mecca and Medina has long made the kingdom a target of terrorist groups who want to wrestle control of them from the kingdom's Western-allied monarchy.

The pilgrimage this year comes as Saudi Arabia faces an expansion of Islamic State group attacks. Two Saudi suicide bombers targeted Shiite pilgrims in eastern Saudi Arabia in May, and a Saudi suicide bomber carried out a third attack in June in neighboring Kuwait. The attacks, which killed 53 people, were claimed by an IS affiliate calling itself "Najd Province," the traditional name for the central heartland of the peninsula.

An IS-claimed suicide bombing last month in Abha, 350 miles south of Mecca, killed 15 people inside a mosque in a police compound. It was the deadliest attack on the kingdom's security forces in years. Eleven of the dead belonged to a counterterrorism unit whose tasks include protecting the hajj.

That attack was claimed by a second alleged IS affiliate in Saudi Arabia calling itself "Hijaz Province" of the Islamic State group, in reference to the traditional name of the western stretch of the Arabian Peninsula.

Al-Turki acknowledged that this year the kingdom saw the most terrorist acts since 2003, when al-Qaida unleashed a wave of bombings that lasted for three years until its militants were driven out to Yemen where they remain active.

Little is publicly known about the structure of the Islamic State group in Saudi Arabia, such as whether militants in the kingdom have direct operational ties with the group's leadership based in its self-declared "caliphate" in Iraq and Syria — or if they simply operate independently in the group's name.

Al-Turki said IS supporters in Saudi Arabia are little more than small "cluster cells" or even individuals inspired by the IS group who find one another by communicating online. He said their claims of having a province or state in Saudi Arabia is nothing more than online propaganda.

"In reality, they cannot control a centimeter anywhere in Saudi Arabia," he said.