Destroyer leader (DL) was the United States Navy designation for large destroyers from 9 February 1951 through the early years of the Cold War. United States ships with hull classification symbol DL were officially frigates from 1 January 1955 until 1975. The smaller destroyer leaders were reclassified as destroyers and the larger as cruisers by the United States Navy 1975 ship reclassification so destroyer escorts could be reclassified as frigates (FF) in conformance with international usage of the term. By the end of World War I the destroyers intended to screen formations of battleships had evolved to a displacement of approximately 1,100 tons armed with four guns and six or more torpedoes. Italy had built three esploratori (scout cruisers) approximately 70% larger than contemporary destroyers. The Washington Naval Treaty encouraged the United Kingdom's satisfaction with its traditional fleet of s and the United States' contentment with the similar and s, while the signatories with smaller fleets explored alternative warship configurations between the classical definitions of destroyer and cruiser. Italy launched three more esploratori and France responded with six Chacal-class contre-torpilleur super destroyers. Japan launched the minimum light cruiser followed by the Fubuki-class special type destroyers 特型 with endurance to escort the Kido Butai mobile force of aircraft carriers over the wide reaches of the Pacific. Germany built similarly enlarged Zerstörer when it commenced naval rearmament. With the exception of the and a few flotilla leaders, most British and American destroyers built between the world wars were smaller than contemporary Axis destroyers; but as the battleships for which the smaller destroyers had been designed as escorts faded into restricted roles in the combat experience of World War II, United States destroyer displacement increased to 2100 tons, 2200 tons, and 2400 tons to support Fast Carrier Task Force operations.