AIPEI, Feb. 20 - China denounced today a declaration by Japan and the United States that they had a "common strategic objective" in the peaceful resolution of issues in the Taiwan Strait, even as Taiwan"s foreign minister cautiously welcomed the statement.

The joint United States-Japan agreement on Saturday was the top news story on it"s the official New China News Agency"s Internet site this afternoon. The article described the joint statement as "unprecedented" and said China"s Foreign Ministry had denounced it.

The Chinese government and people "resolutely" oppose "the United States and Japan in issuing any bilateral document concerning China"s Taiwan, which meddles the internal affairs of China, and hurts China"s sovereignty," the news agency said, citing the Foreign Ministry.

The joint statement made Saturday in Washington, or early this morning China time, included "encouraging the peaceful resolution of issues concerning the Taiwan Strait" in a list of "common strategic objectives" of Japan and the United States.

China has viewed Taiwan as a breakaway province ever since the Nationalists retreated here after losing a civil war to the Communists in 1949.

The United States and Japan have been trying to enlist China in efforts to persuade North Korea to abandon its nuclear weapons program. China is sending a delegation to Pyongyang, and today"s statement by the Chinese Foreign Ministry did not link Chinese cooperation on North Korea to the Taiwan policies of the United States and Japan.

Chen Tan-sun, Taiwan"s foreign minister, said in a telephone interview from his home this morning that the joint statement by the United States and Japan would provide Taiwan with a greater confidence in its security. But he took pains not to present the declaration as a challenge to mainland China.

"We want to emphasize the importance of a peaceful settlement here," he said.

Taiwan has been trying to improve cross-straits relations in the two months since advocates of greater Taiwanese political independence from the mainland suffered an unexpected setback in legislative elections.

Taipei and Beijing agreed to allow flights between the mainland and Taiwan over the lunar new year earlier this month for only the second time, and put fewer restrictions on the flight routes than in 2003, the first time such flights were allowed.

Mr. Chen said that he believed Japanese officials shared Taiwan"s concerns about China"s double-digit annual increases in military spending, especially after the recent detection of a Chinese submarine in waters claimed by Japan. But he added that that the government of Taiwan had not been contacted directly by Tokyo in connection with Saturday"s agreement.

The shift in the Japanese stance on Saturday was fairly subtle. The Japanese government has previously called for peace in the Taiwan Straits, the Japanese government has previously offered logistical but not military support to the United States in case of a conflict between Taiwan and mainland China. Japanese officials were reticent about calling attention to the new language in Saturday"s statement.

Saturday"s statement nonetheless represented a departure from the previous military cooperation statement between the United States and Japan in 1997, which simply called for the two countries to work together in the "area surrounding Japan."

Lo Fu-chen, who was Taiwan"s chief representative to Japan from 2001 until last July, said the new policy statement represented a very important gain for Taiwan. "It"s a giant step for Japan to step in and even mention the Taiwan Strait as a security concern from their viewpoint," said Mr. Lo, who is now the chairman of the Association of East Asian Relations here.