Taiwan leader Ma Ying-jeou visited Taiping Island in the South China Sea on Thursday, showing his determination to safeguard the sovereignty of the islands in the South China Sea. He emphasized that "whether from the perspective of history, geography, or international law," regarding the Nansha, Xisha, Zhongsha and Dongsha Islands, "the ROC (Republic of China) enjoys all rights over these islands and their surrounding waters in accordance with international law. This is indisputable."

As the ruling Kuomintang (KMT) acknowledges that Taiwan and the Chinese mainland belong to one China, Ma's trip signals a positive act in safeguarding Chinese people's territorial sovereignty and maritime interests in the South China Sea.

What has now become the nine-dash line was originally drawn by the government of the then-ROC ruled by the KMT. Since the People's Republic of China was established, the mainland has taken on claiming the rights within the nine-dash line. Taiwan's stance in this regard has been restrained due to external factors. Most of the time, it is the mainland that is at the frontline of guarding the sovereignty of the islands.

Ma had planned to visit Taiping Island last year, but did not make the trip, reportedly due to US objections. He has fulfilled his wish before he steps down. The opposition Democratic Progressive Party (DPP) turned down an invitation from Ma to send an envoy on the trip. The US also expressed disappointment on Thursday.

Under enormous pressure to safeguard the islands China owns dating back to history, the mainland has been acting alone. If Taiwan can join hands with the mainland, China will have the upper hand in this regard. But Taiwan is not willing to do so because the US does not allow it to do so in the South China Sea disputes or the Diaoyu Island issue.

Ma has made efforts for this trip. In 2008 when Chen Shui-bian ruled Taiwan, he visited Taiping Island. But the disputes around the South China Sea were different from today. At least at that time, the US did not intervene publicly. Chen withdrew troops from the island and sent the Coast Guard Administration for law enforcement instead.

Worryingly, if DPP leader Tsai Ing-wen compromises in the South China Sea issue after assuming power, it will add daunting challenges to the mainland. One significance of Ma's trip is to set up a line of defense for Tsai's retreat. It is hard to say right now how much of a role it can play.

Currently, the mainland should not count on Taiwan to do much over the South China Sea and East China Sea issues. But in the long run, the situation may change. Despite political divergences between Taiwan and the mainland, people from both sides have the same roots and economic and cultural exchanges have remained frequent. Taiwan society's old sense of national identity may wake up and Taiwan may become the pioneer to safeguard the Diaoyu and Nansha Islands. Ma visited Taiping Island in a cautious manner, but his step is worth applauding.