Chinese state media said on Monday they were "cautiously optimistic" that in his second term US President Barack Obama would improve ties strained by distrust and fear.

The commentary by the Xinhua state news agency came ahead of the ceremonies for Obama's second inauguration and after Beijing criticised Washington's position in an escalating territorial row between China and Japan.

"The lack of strategic trust has become the main obstacle to a mature China-US relationship," it said.

The US showed distrust, it said, by offering "covert support" to Japan over the islands, "meddling" in disputes between China and Southeast Asian countries, and boosting its military presence in the western Pacific.

Top US diplomat Hillary Clinton said last week that Washington opposed "any unilateral actions that would seek to undermine Japanese administration" of East China Sea islands claimed by Beijing.

Xinhua said that "some US politicians" have always tended to fear their country's biggest perceived rival and "have seen China's emerging role on the world stage with a sense of anxiety".

But while the commentary said Obama, whose public inauguration takes place on Monday, "failed to significantly enhance strategic trust between the two nations" in his first term, it also struck a positive note.

"One can be cautiously optimistic that the president is leaning toward the idea of enhancing the US-China relationship rather than seeking confrontation," it said.

The commentary described the "China challenge" as "a hidden opportunity for his second term and he actually has a good chance of helping shape a new paradigm of inter-power relations and thus making it part of his legacy".

"China has made the first move and now the ball is in the US court," it added.

Xinhua also acknowledged "the historical pattern of the seemingly inevitable conflict between a rising power and an established one" -- echoing similar comments previously made by Clinton.