The uninhabited islands in the East China Sea have become a source of serious territorial contention between Japan and China, and tensions have worsened since Japan nationalized the islands last September. China calls the islands Diaoyu Islands.
Speaking to the media last Friday following her meeting with visiting Japanese Foreign Minister Fumio Kishida, Clinton said she "reiterated longstanding American policy on the Senkaku Islands and our treaty obligations."
She said although the United States does not take a position on the ultimate sovereignty of the islands, "we acknowledge they are under the administration of Japan and we oppose any unilateral actions that would seek to undermine Japanese administration and we urge all parties to take steps to prevent incidents and manage disagreements through peaceful means."
A Xinhua commentary said Clinton's remarks meant the U.S.-Japan Security Treaty applied to the islands.
"Her words showed explicit U.S. endorsement of Japan over the Diaoyu Islands issue, sending a mixed and wrong signal and adding fuel to the matter," Xinhua said, adding: "It was exceedingly wrong for Clinton, a senior U.S. governmental official in charge of American foreign affairs, to make such comments," which were "ignorant of essential historical facts and international law ... ."
The report said the islands have been "China's inherent territories since ancient times."
It said the United States "arbitrarily placed the Diaoyu Islands under its administration in the 1950s and transferred the so-called 'administrative authority' to Japan in the 1970s," adding such "backroom deals" had seriously violated China's territorial sovereignty.
Xinhua said Clinton's words, which "indicated the chaotic U.S. foreign policies," would embolden right-wing forces in Japan and intensify tensions between China and Japan, and that the "irresponsible U.S. remarks concerning the Diaoyu Islands will worsen, rather than relieve the tension over the issue."
The report said with "intensified tension and deteriorated security within the region, no less the prospect of reviving militarism in Japan, the security and economic recovery of the U.S. would be largely affected. It is unwise for the politicians to act shortsightedly."
In an earlier commentary, Xinhua said: "U.S. explicit endorsement of a right-leaning Japan is sure to raise concerns among Asian countries, many of which still hold bitter memories of Japan's wartime atrocities and are casting a wary eye on the newly installed hawkish administration in Tokyo."
The reference was to the new Japanese government led by Prime Minister Shinzo Abe, who has taken a tough stand on the island dispute.
In her comments, Clinton also said her government has invited Abe to visit the United States and meet with President Obama in the third week of February. Abe's earlier planned visit this month had to be put off due to Obama's busy schedule.
Kishida said the security environment is becoming "ever more challenging in the Asia Pacific," and that his government recognizes that the "close Japan-U.S. cooperation in all areas is indispensable."
He said that while Japan "will not concede and will uphold our fundamental position that the Senkaku Islands are an inherent territory of Japan, we intend to respond calmly so as not to provoke China."