BEIJING -- Safeguarding China's territorial sovereignty over the Diaoyu Islands is the shared responsibility of compatriots across the Taiwan Strait, a mainland official said Wednesday.

Yang Yi, spokesman for the State Council's Taiwan Affairs Office, made the remarks at a press conference in response to some Taiwanese Democratic Progressive Party (DPP) and Taiwan Solidarity Union (TSU) members' recent statements that Taiwan should not team up with the mainland to challenge Japan or the Japanese-U.S. security alliance.

Yang warned that history will be the judge of people's words and actions today, adding that if anyone forgets his own ancestors and betrays the common good of the Chinese nation, he will eventually be despised by the Chinese people.

On Jan. 24, a group of activists from Taiwan used their fishing vessel to sail to the waters surrounding the Diaoyu Islands, planning to declare sovereignty over the islands.

Yang also commented on speculation that Raymond F. Burchard, chairman of the American Institute in Taiwan, may bring up topics including a trade and investment agreement between the U.S. and Taiwan, as well as U.S. arms sales to Taiwan, during his upcoming visit to the island.

Yang said the U.S. side is expected to uphold the one-China policy and refrain from establishing any type of official ties with Taiwan, and the mainland resolutely opposes U.S. arms sales to Taiwan.

Yang also commented on some retired Taiwanese military officers' proposals to institutionalize cross-Strait military exchanges, saying proposals from Taiwan compatriots in all social sectors on developing cross-Strait relations are welcome.