US is not the peace maker in this case.
if it were really a peacemaker, first it would gone back and public and say that it made a mistake in transferring the administration of rocks back to Japan. Second. would not encourage japan by saying US-Japan Alliance covers a territory Japan has clearly has a dispute on, while at same time saying that it is neutral in this dispute. If you lend your buddy the a gun and promise to come to his aid if he is in trouble, while same time saying you are not in his argument with his neighbor, is, by all stretch of common sense, a bald face lie. And it should called so, and subsequently lose all of its moral high ground in this case.
Apeace maker does not mean to intimate one side while give the other side a blank check grantee. a good peacemaker would absolve itself of all interest in the dispute (in which clearly US in this case is not the case because preserving a strong japan vs a weak china is clearly in US interest, hence all the bullshchit about Preserving the Status Quo, which a code word for the current absolute Supreme dominance of Western Pacfic air and sea space by the US-Japan Military Alliance ), a TRUE peace maker would go back to the merit of the issue, and judge and act base on the merit and merit alone not politics. Clearly US is not in the condition to do so. Simply the echos of NSC-68 and Dean G. Acheson's famous speech at the National Press Club on 12 January 1950, which was seen as putting Taiwan and South Korea outside of US defensive parameter, would prohibited US from even a slightest waiver in its position less it is seen as analogous to the historic "Appeasement"... So sadly, Chinese aspirations would suffer instead, and merely a delaying of inevitable would ensure. simply put it, US-Japan is writing checks its grandkids would not be able to cash...
The Core of the problem is that, it is trying to preserve its own disproportionate interest vis-a-via a power in Asia by preserving its alliance with a country governed by the most notorious nationalistic government since 1945. by doing so I found it very hard to convince history that It is doing the right thing. It has let go of all but thinnest veils of universal values covering a grotesque body of naked national interest and may be even racial hatred.
P.S.
I would find it surprising that all the media lynching of china on this issue lately is not with out an active spin by the US government or interest groups in and around it.