The Marines have chosen to get rid of all of their tanks, most of their tube artillery, and a large amount of aviation units. These will be replaced with more long-range rocket artillery and anti-ship missiles in order to prepare for possible island hopping in the South Pacific. The service has identified China as a pacing threat and wants to prepare for a possible conflict in the South China Sea. Recently China has been building their presence in the area with increased aircraft carriers and established military installations on surrounding islands. The islands in the South China Sea have been deemed too small to properly employ tanks and heavy cannon artillery.
Source: https://www.popularmechanics.com/military/weapons/a31915295/marine-corps-tanks/
