They can help, but they are no game-changer for Taipei.
Why New Submarines Alone Won't Save Taiwan from China
After its long request for additional submarines, Taiwan has somehow progressed towards its goal. On May 9, the groundbreaking ceremony of the shipyard for building submarines in Kaohsiung represented a milestone for Taiwan’s indigenous project. After the fleet is completed, the asymmetrical nature of the submarines vis-à-vis the Chinese major surface naval ships would strengthen Taipei’s deterrence against Beijing. The underwater environment also makes the fleet generally free from air cover. In the face of the advancing firepower of missiles and other projectiles from the People’s Liberation Army (PLA), Taiwan’s air bases could be vulnerable, as the quantitatively superior combat aircraft of the PLA Air Force (PLAAF) and PLA Navy (PLAN) would seriously challenge Taiwan’s air defenses as well.
In case that the PLA really dominated the sky above the island and even sent airborne some units to the island, the eventual shipping massive force across the Strait is still indispensable. In this scenario, a few submarines could significantly disrupt, if not deny, the PLAN amphibious fleet from projecting troops onshore, thus causing considerable uncertainty for Beijing’s gambit. Apart from surface vessels, sub-launched cruise missiles would further amplify the strategic values of the submarines beyond the maritime domain, meaning more costs for China regarding use of force.