Much has been written in recent months concerning the bilateral training effort between the U.S Navy's antisubmarine forces and the Swedish attack submarine HMS Gotland , which has been exercising with the Pacific Fleet since 2005. Since 2001, however, the U.S. Navy has also been engaged with the submarine communities of various world navies under the innovative Diesel Electric Submarine Initiative (DESI). Under this initiative, U.S. warships are able to conduct training exercises with diesel submarine forces from allied, mostly South American, fleets. To date, nearly 20 non-nuclear submarine operating nations have taken part in exercises aimed at providing antisubmarine warfare training to U.S. Navy aircraft carrier and expeditionary strike groups. The most recent of these exercises took place with Colombia's Type 209/1200-class submarine Tayrona , shown here. The submarine, in service with the Colombian fleet since 1975, teamed up with the Ticonderoga (CG-47)-class cruiser USS Vicksburg (CG-69) and operated for ten days off the coast of Mayport, Florida.