After the visit of Tibet's peace envoy to Chang-an, the situation changed greatly. In February 675 the general Li Kun-haeng invaded the Imgin river and set up the military strongholds. Fierce battles occurred there and the political situation was against Silla. But the destruction of T'ang's supply ships by Silia changed the situation. The naval force of Silia pursued the supply ships of T'ang during the war. It was certain that the possibility of the supply route being cut off was considered seriously by the Silla court. After hearing the news of the sunk ships, the morale of the T'ang's army began to erode and caused the withdrawal of T'ang's army. But domestic discord in Tibet, started at the end of 675, gave T'ang a chance to deliver a blow to its enemy. In 676 general Li Kun-haeng, who commanded T'ang's Malgal army in Korea, was dispatched to Tibet. The death of the Tibetan King in 676 led to a succession dispute. Power struggles over the throne started between the queen and mGar. The news of the conflicts in Tibet reached the T'ang's court. The Chinese emperor wished to take advantage of the situation to attack the Tibetan army. From that time T'ang watched Tibet, with no possibiliry of invading Silia. The T'ang and Silla war was caused by the T'ang and Tibet war over the control of silkroad. Even though the T'ang and Silla war ended in 676, the possibility for war remained, which was seen by the weaker Silla as a truce. Seen from Silla's perspective, the invasion of T'ang was more than a possibility. That made Silla to rapidly build-up its military and have a peaceful diplomacy with Japan.