What constitutes an attack and what constitutes Taiwan?

For example: there are various islands in the Taiwan Strait that are disputed, some already under the control of the PRC and some under the control of the ROC. For example: https://en.m.wikipedia.org/wiki/Dadeng_Subdistrict

Would a landing on an unoccupied disputed island by PRC forces be considered an attack on Taiwan?

If not, how big of an attack would count to resolve this YES? For example, if the PRC invaded https://en.m.wikipedia.org/wiki/Dongding_Island, would that count?