Tehran said on Sunday it carried out a third day of retaliatory strikes against US attacks on Iranian territory, as both accused the other of violating their fragile ceasefire, straining negotiations meant to end the Middle East war. The exchanges underscored the fragility of a Pakistan-brokered peace process aimed at ending a war launched by the United States and Israel in February, which disrupted shipping through the Strait of Hormuz and rattled global energy markets. Iran’s Islamic Revolutionary Guard Corps (IRGC) said on Sunday they were taking measures to control traffic in the vital Strait of Hormuz and that violating vessels would be dealt with more firmly than before.