Digist
美国海军推出四支柱战略，以加快弗吉尼亚级和哥伦比亚级潜艇的生产并推动其更快加入舰队。
U.S Navy Announces 4-Pillar Strategy To Hasten Production Of Virginia & Columbia Class Submarines
U.S. has come up with a 4-pillar strategic initiative to increase the pace of submarine production and their entry into the naval fleet.