Story highlights Outgoing President Ma visits Taiping Island, also known as Itu Aba

The island is part of the Spratly archipelago, claimed by multiple countries in the region

U.S. says president's trip is "extremely unhelpful"

Hong Kong (CNN) Taiwan's president has paid a visit to an island in disputed waters in the South China Sea, in a show of sovereignty that has drawn criticism from the United States.

Outgoing President Ma Ying-jeou landed Thursday on Taiping Island, also known as Itu Aba, a small land mass it controls more than 990 miles (1,600 km) south of Taiwan in the Spratly islands archipelago, the Office of the President said.

Vietnam, the Philippines, Malaysia and Brunei also lay claim to all or part of the Spratlys, while China claims most of the South China Sea.

President Ma met with coastguard personnel and said that several islands in the disputed waters belonged to the Republic of China (ROC) -- Taiwan's official name. He pledged to resolve disputes peacefully.

"The Nansha (Spratly) Islands, Shisha (Paracel) Islands, Chungsha (Macclesfield Bank) Islands, and Tungsha (Pratas) Islands, as well as their surrounding waters, are an inherent part of ROC territory and waters, and the ROC enjoys all rights over these islands and their surrounding waters in accordance with international law. This is indisputable," Ma said, according to a statement.