The sailing of a US warship within an area claimed by China last week angered Beijing, which issued a warning.
Adm Harry Harris, speaking in Beijing, said such moves should surprise no-one.
An unnamed US official earlier told Reuters similar patrols would take place at least "twice a quarter".
The guided-missile destroyer USS Lassen breached the 12-nautical mile zone that China claims around the Subi and Mischief reefs in the Spratly archipelago.