New York City Mayor Bill de Blasio spoke at a police graduation ceremony today, and for the most part, it was civil.

But while cadets sat at attention facing de Blasio, there were some heckles and boos from an area where friends and family members were sitting.

There’s been tension between the mayor and rank-and-file New York City police lately because of protests over the chokehold death of an unarmed black man at the hands of a police officer.

Union leaders say de Blasio has generated an anti-police atmosphere with some of his comments about the demonstrations, and that his handling of the situation contributed to the shooting deaths of two police officers who were sitting in their crusier in Brooklyn. 

At Monday’s graduation ceremony in Madison Square Garden, the mayor praised the incoming officers and promised to equip them with everything they need to do their job.