Not to be confused with People's Liberation Army Navy (PLAN), the naval forces of the People's Republic of China (PRC).The Republic of China Navy is the maritime branch of the Armed forces of the Republic of China (Taiwan). The ROC Navy's primary mission is to defend ROC territories and the sea lanes that surround Taiwan against a blockade, attack, or possible invasion by forces of the People's Republic of China. Operations include maritime patrols in the Taiwan Strait and surrounding waters, as well as counter-strike and counter-invasion operations during wartime. The Republic of China Marine Corps functions as a branch of the Navy. The ship prefix for ROCN combatants is ROCS (Republic of China Ship); an older usage is CNS (Chinese Navy Ship).
This nice card showing three of ROC Navy’s ships alongside was sent to me by YuLing.