A group of "lawmakers" from the Democratic Progressive Party (DPP) and Kuomintang (KMT) in Taiwan visited Taiping Island in the South China Sea on Wednesday, a move experts said shows Taiwan's resolve to protect ancestral assets and to help soften relations with the Chinese mainland.

A delegation led by KMT legislator and convener of "the Legislature's Foreign Affairs and National Defense Committee" Chiang Chi-chen rode a military airplane from southern Taiwan's Pingtung and completed a tour of Taiping Island on Wednesday, reported Focus Taiwan, the English website of Taiwan-based Central News Agency.

The group observed military facilities on the island and a newly built harbor and hardware facilities, said Chiang, adding that they were "convinced" that Taiping is an island, not a rock.

The visit comes on the heels of the decision of the Arbitral Tribunal in The Hague on the South China Sea, which said all high-tide features in the South China Sea, including Taiping, are rocks rather than islands.

Taiping, the largest land area of the Nansha Islands, is believed to be an "island" as it covers 510 square meters, has fresh water and is believed to be inhabitable. Under international law, an island is entitled to a 200-nautical-mile economic zone.

"The award has angered the mainland and Taiwan residents. And it goes against KMT policies to protect ancestral assets," Zhang Hua, an assistant research fellow at the Institute of Taiwan Studies under the Chinese Academy of Social Sciences (CASS), told the Global Times on Wednesday.

Zhang said that [by emphasizing sovereignty over Taiping] the KMT could pressure the ruling DPP as well as gain political influence in Taiwan.

Ma Ying-jeou, former Taiwan leader and KMT head, visited Taiping in January and reaffirmed Taiwan's sovereignty over the island and its surrounding waters, according to the Xinhua News Agency.

Some DPP members opposed the Taiping visits since they don't want to share the same interests with the mainland, offend any ASEAN country or hinder the US Asia-Pacific strategy, Jin Yi, an expert from the Institute of Taiwan Studies at the CASS, told the Global Times on Wednesday.

The Wednesday trip included four KMT legislators and four from the DPP.

Wang Ting-yu, a DPP legislator, was quoted by Focus Taiwan as saying there are solar power generation facilities, a new wharf, as well as indigenous plants and trees on the island, and that "there is no question about the sovereignty of the island, or its status as an island."

According to a poll conducted by Taiwan-based satellite television channel and cable TV network TVBS, 65 percent of Taiwan residents support a visit by the island's leader Tsai Ing-wen to Taiping to highlight sovereignty.

"Tsai and the DPP have long been criticized for their weak efforts to safeguard Taiwan's interests in the South China Sea. And this trip may ease pressure from Taiwan and also provide her leeway to avoid enraging the US," said Jin.

Tsai has vowed to defend the island's sovereignty over Taiping Island by sending a frigate to patrol the South China Sea, and rejecting the arbitral ruling, saying that the award is not legally binding, Taiwan's Central News Agency reported.

Common stance

Jin said the Taiping trip shows that Taiwan has the same stance as the Chinese mainland on the South China Sea issue, and that it would benefit the mainland's current efforts to uphold sovereignty in the region.

The visit helps contain the ruling DPP if some of its members want to limit "Taiwan sovereignty" over Taiping Island and nearby islands, in a bid to split the link with the mainland on the South China Sea, said Jin.

The Nine-Dash-Line that marks China's territory in the South China Sea dates back to the 1940s during KMT rule.

Five Taiwan fishing boats also joined the Taiping trip, Taiwan media reported.

Lo Keung-fei, who joined the trip, told the Liberty Times newspaper that their trip was aimed at protecting fishing rights around Taiping's 200-nautical-mile economic zone and to urge the Taiwan authorities to take a tough stance on sovereignty.

Banners on the boats declared "protect ancestral assets," Focus Taiwan reported.

"It shows the determination of the mainland and Taiwan to defend the Chinese nation's interests. And this is a great opportunity to improve cross-Straits relations," said Zhang, adding that there should be more cooperation across the Taiwan Straits on the South China Sea issue.

Wang Jianmin, a cross-Straits scholar at CASS, said in an article in the Xiamen-based Strait Herald that the Chinese mainland and Taiwan could start with jointly developing fishing, oil and gas exploration and ecological protection.

Both sides could also discuss the possibility on setting up a mutually acceptable military security mechanism and explore joint patrols in the South China Sea, Wang said.

Lu Kang, Chinese foreign ministry spokesperson, said earlier that "Chinese people on both sides of the Taiwan Straits have a responsibility to protect their ancestral property."