The Second Taiwan Strait Crisis began on 23 August 1958, with air and naval engagements between the PRC and the ROC military forces, leading to intense artillery bombardment of Quemoy (by the PRC) and Amoy (by the ROC), and ended on November of the same year. PLA patrol boats blockaded the islands, keeping out ROC supply ships. Though the United States rejected Chiang Kai-shek's proposal to bomb mainland China artillery batteries, it quickly moved to supply fighter jets and anti-aircraft missiles to the ROC. It also provided amphibious assault ships to land supplies, as a sunken ROC naval vessel was blocking the harbor. On September 7 the United States escorted a convoy of ROC supply ships and the PRC refrained from firing. On October 25 the PRC announced an "even-day ceasefire" — the PLA would only shell Quemoy on odd-numbered days. Despite the end of the hostilities, the two sides have never signed any agreement or treaty to officially end the war.