Two Taiwanese coast guard patrol ships have sailed to waters near a disputed island chain in the East China Sea to assert Taiwan's claim to it, AP reported. The coast guard said the ships sailed Thursday to waters 25 nautical miles west of the chain to demonstrate the coast guard's ability to protect local fishermen. The chain - known as Senkaku in Japan and Diaoyu in China - is controlled by Japan but also claimed by China and Taiwan. Japan's government purchased several of the islands from their private owners this week. China called the purchase "null and void" and threatened "serious consequences." Reporters on the Taiwanese ships said the coast guard showed off machine guns on the deck but didn't fire shots. No confrontation with the Japanese coast guard was reported.