The Diaoyutai is a disputed territory and Panetta clearly says the US defense treaty with Japan does not cover such territories.
You clearly do not understand the difference between "sovereignty" and "administration". The defense treaty covers the "administration" part and has nothing to do with "sovereignty claims". Who cares if the Diaoyudai is disputed? It is clearly under the Japanese administration and that alone qualifies the invocation of the 5th article of the defense treaty. Japan can claim the Liancourt Rocks and Kurils all they want, but the defense treaty doesn't cover those because they are not administered by Japan.
Panetta said that the US had certain obligations under the defense treaty on Diaoyudai, so what obligation is he talking about?obviously, we stand by our treaty obligations,” Panetta said.