RIMPAC 2022 Amphibious Raid

From right, an AH-1Z Viper, attached to Marine Light Attack Helicopter Squadron (HMLA) 169, a UH-1Y Huey, attached to HMLA 169, an MV-22B Osprey, attached to Marine Medium Tiltrotor Squadron (VMM) 363, and a CH-53E, attached to Marine Heavy Helicopter Squadron (HMH) 462, participate in flight operations from the flight deck of U.S. Navy Wasp-class amphibious assault ship USS Essex (LHD 2) in support of an amphibious operations exercise during Rim of the Pacific (RIMPAC) 2022, July 29. Twenty-six nations, 38 ships, three submarines, more than 170 aircraft and 25,000 personnel are participating in RIMPAC from June 29 to Aug. 4 in and around the Hawaiian Islands and Southern California. The world's largest international maritime exercise, RIMPAC provides a unique training opportunity while fostering and sustaining cooperative relationships among participants critical to ensuring the safety of sea lanes and security on the world's oceans. RIMPAC 2022 is the 28th exercise in the series that began in 1971. (U.S. Navy photo by Mass Communication Specialist 2nd Class Brett McMinoway)

 Republic of Korea Navy Amphibious Assault Vehicles (AAV) and U.S. Navy and Marine Corps aircraft conduct amphibious operations during Rim of the Pacific (RIMPAC) 2022, July 29, during an amphibious raid. Twenty-six nations, 38 ships, three submarines, more than 170 aircraft and 25,000 personnel are participating in RIMPAC from June 29 to Aug. 4 in and around the Hawaiian Islands and Southern California. The world's largest international maritime exercise, RIMPAC provides a unique training opportunity while fostering and sustaining cooperative relationships among participants critical to ensuring the safety of sea lanes and security on the world's oceans. RIMPAC 2022 is the 28th exercise in the series that began in 1971. (U.S. Navy photo by Mass Communication Specialist 3rd Class Isaak Martinez)

How are the S. Koreans able to keep their AAVs "swimmable" and yet the Marine Corps was incapable?  Not sure if its a vehicle problem, an excuse for doctrine change or poor leadership/planning.