One of the most humiliating treaties of inequality that Qing Dynasty had signed with imperialists was granting cabotage for foreign vessels sailing into inland rivers of China.  Although before the end of WWII UK and the US agreed to give up those treaties imposed on China, in fact their warships still navigated in Long River freely after the War.  Chiang regime was not able nor willing to address the problem at all. 

Time was in April, 1949 when PLA was ready to ferry across Long River, the "Purple Quartz(?) Incident" took place.  Kindly read the following story at:

https://www.toutiao.com/a6765750036451033603/

PS  Is Strait of Taiwan an inland channel?  May be not.  But whenever needed, any foreign interference on China internal affairs will be served by long-ranged rockets and missiles, not cannons any more, as long as "Thought and Spirit of Mao" remains!