Kenya said on Sunday it may deploy as many as 10,000 police officers to boost security during a visit by Pope Francis later this month as the country readies for crowds of one million people.

Islamist rebels have staged a string of attacks in Kenya, including the April massacre at Garissa university in which 148 people were killed, and the 2013 assault on Nairobi’s Westgate shopping mall that killed 67.

“Security agencies continue to fine-tune plans to secure the city during a particularly busy period, and when we expect Nairobi’s population to swell by an additional one million people,” State House spokesman Manoah Esipisu said in a statement.

“Tentatively, some 10,000 police officers will be deployed,” Esipisu said, adding that another 10,000 members of the government’s youth service would help in crowd control.

The pontiff will be in Kenya from November 25 to 27, before spending two days in Uganda and travelling to the Central African Republic (CAR), where his trip will end on November 30, according to a Vatican itinerary.

The three countries — which have significant Catholic communities — have been troubled by civil conflicts and violence, leading to increased security concerns surrounding the pope’s visit.

In Nairobi, Francis will tour the Kangemi district, home to some 100,000 people who live in shacks without proper sewage systems and where some 20,000 residents belong to the local Catholic parish.