Two Chinese vessels prevented an Indonesian patrol boat from impounding a Chinese fishing vessel near the Natuna Islands on March 19. Indonesia claims the vessel was trespassing in its exclusive economic zone, but China asserts that the area is its traditional fishing ground. Though Indonesian authorities failed to impound the ship, they did arrest the fishermen. Officials also threatened to appeal to an international court of arbitration and respond to future incidents with larger vessels. In a similar event March 25, about 100 Chinese fishing boats were detected allegedly encroaching on waters near the Luconia Shoals, which Malaysia administers but China claims. Two Chinese coast guard vessels were reportedly guarding the fishing boats. Malaysia's navy monitored the situation, threatening legal action if the boats trespassed into its exclusive economic zone. But China's Foreign Ministry again reiterated Chinese fishing boats' rights to operate in the area.