The guided-missile destroyer arrived in the Gulf of Tonkin, via Pearl Harbor, Guam, and Subic Bay, on 3 May. There, she joined other 7th Fleet units in heavy attacks against North Vietnamese military units pushing south along the coast. After firing numerous bombardment missions against enemy troops and tanks advancing toward Hue, "Berkeley" joined Operation Pocket Money, the mining of the river approaches to Haiphong, North Vietnam, on 9 May. In company with five other destroyers, the warship closed Haiphong to provide a protective barrage of 5-inch shells as A-6 Intruders and A-7 Corsairs from "Coral Sea" dropped magnetic-acoustic sea mines off that port.