HONG KONG — The Chinese military began sending a new group of troops into Hong Kong on Thursday, a move it described as a normal annual rotation of its garrison in the city, but one that was being closely watched because of the local political turmoil.

The move came hours before two organizers of the protests that have roiled the city said they were attacked, in separate incidents, by men with makeshift weapons, one in a restaurant and the other while giving an interview on a sidewalk. Also Thursday, the police denied a protest group permission to hold another large march through the city this weekend.

Chinese state-run media published photos and video of the troop movement, showing trucks, armored personnel carriers and a ship entering Hong Kong under cover of early-morning darkness.

“This rotation is an annual normal routine action approved by the Central Military Commission,” Lt. Col. Han You, a spokesman for the Hong Kong garrison of the People’s Liberation Army, said in a written statement. In recent years, the garrison has indeed carried out its rotation at the end of August.