The US Senate's backing last week for Japan's administration of the disputed East China Sea islands will only escalate tensions between Beijing and Tokyo, Chinese analysts say.
Beijing has yet to officially respond, but Xinhua yesterday carried a commentary that said the senators' attempt to "fish in troubled waters will not succeed".
The senate's backing for Tokyo, through a vote on a legal amendment, has been widely covered in mainland media, prompting comments by Chinese internet users attacking the United States for interfering.
The US Senate unanimously backed the amendment, introduced by a long-time critic of China, Democrat senator Jim Webb. The measure notes that while the US "takes no position" on the ultimate sovereignty of the Diaoyu Islands, which Japan calls the Senkakus, it "acknowledges the administration of Japan over the Senkaku Islands". It also notes that "unilateral actions of a third party" would not affect US acknowledgement of Japan's administration of the islands.
It reaffirms the US commitment to Japan under the Treaty of Mutual Co-operation and Security and warns that an armed attack against either party "in the territories under the administration of Japan" would be met in accordance with its provisions.
In September Kurt Campbell, the US assistant secretary of state for East Asian and Pacific affairs, told a Senate sub-committee that the 1960 treaty obliged the US to come to Japan's aid if attacked.
Xinhua's commentary said the senators were pouring oil on a fire and "trying to contain China, which had claimed sovereignty over the Diaoyus", but that Thursday's vote would backfire.
The vote was the top item on mainland news portals yesterday. On sohu.com  the story had attracted more than 270,000 clicks and more than 62,000 messages criticising the US.
Liu Jiangyong , a professor of international relations at Tsinghua University in Beijing, said the senate's decision would only stoke tensions. He said if the US president, Barack Obama, signed the amendment into law, it would have "grave consequences for Sino-US and Sino-Japanese relations".
"It is sowing tension and will put Beijing and Tokyo at loggerheads," Liu said. "Japan is not the sole country controlling the waters off the Diaoyu Islands. Our coastguard vessels and fishing boats have entered the archipelago's waters as part of China's sovereignty declaration."
The amendment was attached to the National Defence Authorisation Act for the 2013 financial year, which the senate is still debating.
Japan's Kyodo News reported that the Senate's decision was intended to keep China's moves to assert its claim in check.
Richard Hu, an associate professor in the University of Hong Kong's politics and public administration department, said China still had time to lobby against the amendment. "China has enough time to use its political influence by putting pressure on the White House, lobbying US congressmen and using other measures to stop it from being passed," Hu said.