Chiang's forces had been, as always, making covert actions on the mainland with small numbers of troops, but this event was nothing new and they were not conducted frequently or on a large scale. There were proposals to further expand the facilities on Quemoy and Matsu, so as to make it a true staging area to carry out a re-taking of the mainland, but these ideas were not carried out, and were largely opposed by the US. .
The Nationalist forces did go on alert on 17 July 1958, and this did heighten the tension in the area, however, Nationalist forces did not carry out any large military actions against the PRC in July. Both Chiang's and U.S. forces went on alert because of intelligence hinting at a PRC attack against the Nationalists. In late July the Nationalist's army began a large six-day drill, which also added to the concerns of the communists. Mao used this alert status and the drill to claim that the US and the ROC were preparing to move against the PRC, since there were such a large number of troops moving around the area. Mao and the other communist leaders might have perceived this drill and alert as an actual attempt to mobilize for action against the communist positions since there was an overall increase in military activity in the Taiwan Straits area. This concern led to one of the justifications that Mao used to pursue military actions against Quemoy and Matsu. .
A factor that played into the decision to shell the islands was that a continued PRC acquiescence to the presence of Chiang's troops on Quemoy and Matsu would have led to a de-facto acceptance of the status quo, with the Nationalists becoming firmly encamped in their positions. This meant that a "Two China" policy would emerge, with the possibility of other countries believing that the PRC would accept a "Two China" policy. Non-aggression on the part of the PRC would lead to an undeclared truce emerging with the likelihood of it becoming permanent, because the PRC would be leaving the Nationalist forces unchallenged just a few miles off the coast of mainland China.
