Belfast (PF-35) was laid down on 26 March 1943, at Wilmington, California, by the Consolidated Steel Corporation under a Maritime Commission contract (MC hull 1446).

[2] Following outfitting, shakedown, and post-shakedown repairs, Belfast stood out of San Pedro, California, on 30 April 1944 and headed for Australia.

Belfast continued to operate in the waters around western New Guinea until sent to escort a reinforcement convoy to Leyte in the Philippine Islands during October 1944.

Near the end of 1944, she headed back to the United States and arrived at Boston, Massachusetts, on 24 January 1945 for extensive repairs lasting until spring.

Ogden had to return to Seattle for repairs, but Belfast and the other four frigates arrived at Womens Bay, Kodiak, on 11 June 1945.

On 15 July 1945, EK-3 departed Cold Bay in company with nine of her sister ships – EK-1 (ex-Charlottesville), EK-2 (ex-Long Beach), EK-4 (ex-Machias), EK-5 (ex-San Pedro), 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.