The recent ruling made by an arbitral tribunal on a case initiated by the Philippines, which rejects China's Nine-Dash Line in the South China Sea as illegal and takes Taiping Island inhabited by Taiwan fishermen as a "rock" rather than an "island", offers an opportunity for both sides of the Taiwan Straits to build up basic mutual trust again.

Taiwan's new leader Tsai Ing-wen's unwillingness to accept the 1992 Consensus and its core principle of one China has dented political trust with the mainland, which was further undermined by the "accidental" firing of a missile from Taiwan in the direction of the mainland.

Any cross-Straits discord will offer an opportunity for outside forces to take advantage of it and thus erode the rights and interests of the Chinese nation in the South China Sea. The establishment of mutual trust will help both sides offer each other mutual support at a critical time and jointly safeguard the interests of the Chinese nation.

The unfavorable award by the tribunal is only the latest stage in the South China Sea disputes. Forcible interventions from the United States and other external forces may further escalate tensions in the region.

Under the pretext of the ruling, the Philippines and Vietnam may raise more unreasonable claims in the sea. For both the mainland and Taiwan, the real challenge following the award has just begun, and so they should deepen mutual trust to make sure they are better braced to defend China's legitimate rights and interests in the South China Sea.

In doing so, this "common challenge", if properly handled, can help both sides, especially Taiwan, to realize the importance of their mutual trust again.