She performed escort duty briefly in the Admiralty Islands at the beginning of April 1944, and at the end of the month became part of forces attempting to consolidate the western New Guinea area.

Her first mission took her to Hollandia, and she subsequently advanced to Biak in June 1944, Noemfoor Island in July 1944, and Cape Sansapor in August 1944.

On 18 October 1944, San Pedro departed with a convoy bound for the initial assault on Leyte in the Philippine Islands.

On 15 July 1945, EK-5 departed Cold Bay in company with nine of her sister ships – EK-1 (ex-Charlottesville), EK-2 (ex-Long Beach), EK-3 (ex-Belfast), EK-4 (ex-Machias), EK-6 (ex-Glendale), EK-7 (ex-Sandusky), EK-8 (ex-Coronado), EK-9 (ex-Allentown), and EK-10 (ex-Ogden) – bound for Petropavlovsk-Kamchatsky in the Soviet Union.

[6] In February 1946, the United States began negotiations for the return of ships loaned to the Soviet Union for use during World War II.

Later reclassified as an "auxiliary stock craft" and renamed YAC-23,[8] the ship was decommissioned on 1 April 1977, and returned to United States custody on 26 July 1978.