Submarine incident off Kildin Island

The collision occurred at 8:16 pm local time,[8] at a point slightly over 12 miles from the shoreline, in waters that the United States regarded as international, and that Russia considered as five miles inside the Russian territorial sea (due to the Russian use of a straight baseline). The mission of Baton Rouge off Severomorsk was reportedly the recovery or delivery of intelligence-monitoring devices on the seabed.[7] The American press claimed that the submarine had been checking wireless traffic between Russian bases,[9] but the Russian counterpart asserted that the two boats were engaged in a 'cat-and-mouse game',[10] an opinion also supported by several Western sources.[11][12] According to naval analyst Eugene Miasnikov, the amount of antisubmarine surveillance deployed by the Russians along their shores makes the first possibility implausible. He asserts that the second argument also seems to be weak given the circumstances and that the collision itself seemed to have happened by chance. The breaking waves and the shallow waters of that area of the Barents sea prevented early enemy detection by either submarine. At the time of the incident, both vessels were using only passive sonars.[13] Miasnikov maintains that the submarines of the Los Angeles class are unable to detect acoustic signals from targets located within a cone of 60 degrees astern, thus the most probable scenario was that Kostroma approached Baton Rouge from behind. Indeed, the collision took place when the Kostroma was surfacing, hitting the US submarine underneath on her aft section. The Sierra class sonar is also ‘deaf’ to the aft direction; her usual pattern of acoustic search is moving along a loop course. The incident, however, implied that Russian attack submarines are capable of avoiding passive acoustic detection, at least under certain conditions.[7]

A Sierra-class submarine

Both submarines sustained damage, but no casualties were reported. Russian reports and American aerial surveillance agree that Kostroma's sail was dented on her front section. Russian navy sources reportedly found pieces of composite material from Baton Rouge's anti-sonar tiles.[7][14] The US Navy claimed that besides some scratches, dents, and two minor cuts on her port ballast tank,[15] Baton Rouge did not suffer major damage. But in any case, it was serious since any rupture on the single hull of Baton Rouge would have compromised her pressure resistance.[14] The deactivation of Baton Rouge was announced on 17 September 1993,[16] although some sources claim that the American submarine had already been taken out of service less than a year after the incident,[17] in January 1993.[18] According to Gregory Stitz, curator of Arkansas Inland Maritime Museum,[2] and some European sources,[1] the costs of repairing the damaged pressure hull, along with a programmed refueling, were well beyond the planned budget. Therefore, the US Navy chose to decommission the submarine. Russian naval officers alleged that the US submarine had become a constructive total loss right after the collision.[19] Baton Rouge was deactivated at Mare Island shipyard on 1 November 1993 and eventually scrapped at the Puget Sound Naval Shipyard in Bremerton, Washington.[20] As for Kostroma, she was laid up on 28 March 1992 and had been fully repaired at Nerpa shipyards in Snezhnogorsk by 29 June 1992. The Russian submarine was temporarily renamed Krab, before recovering her original name in November 1996. After a huge overhaul, again at Nerpa, she returned to service in 2005.[21]