ROME — On a perfect May afternoon, with the Roman sunlight glinting off the ancient arches of the Colosseum, Officer Pang Bo adjusted his sunglasses and began his patrol. More or less. He walked around. He looked at tourists, and a few tourists looked at him. He posed for a few photographs.

In his dark-blue uniform and cap, Officer Pang is a top supervisor in one of China’s biggest police departments, in the southern metropolis of Guangzhou. But for two weeks, he and three other Chinese police officers are in Italy with strict orders: to protect Chinese tourists.

That is, even if it isn’t completely clear how four Chinese cops divided between Rome and Milan can make a difference. Or what the tourists need to be protected from.

“The first day when we patrolled, the Chinese tourists saw us, and they were amazed,” said Officer Pang, 44.