`` Kuma '' was on anti-submarine warfare Hostile_encounter exercises Practice .

The Third Cod War Hostile_encounter concluded Process_end in 1976 , with a highly favourable agreement Sign_agreement for Iceland ; the United Kingdom conceded Agree_or_refuse_to_act to a Icelandic exclusive fishery zone after threats Warning that Iceland would withdraw Escaping from NATO , which would have forfeited Preventing_or_letting NATO 's access to most of the GIUK gap , a critical anti-submarine warfare Hostile_encounter during the Cold War .

On the night of 31 May – 1 June , three `` Ko-hyoteki '' -class midget submarines , each with a two-member crew , entered Arriving Sydney Harbour , avoided Preventing_or_letting the partially constructed Sydney Harbour anti-submarine boom net Earnings_and_losses , and attempted to sink Motion_directional Allied warships .