That's a strong case, indeed, because, if the US fails to provide protection to PH, then, what would Japan think of its own security arrangement.
But, on the other hand, like everything in international life, security is also a hierarchical phenomenon. Perhaps, the treaty with Japan means a lot more for the US than the security treaty with PH. It might as well be that the US recalibrates its security treaties based on the national capabilities of target adversary, in this case, CN.
Punishing Iraq for the invasion of Kuwait is one thing. Putting people in the line of fire for PH's territorial claims is quite another, especially given that the dispute is multilateral, not singularly between CH and PH; but also between PH and VN, among others.
