Well, the Philippines surely hasn't been left out of our defense perimeter in the western Pacific:
"Of course, we would help you," [Admiral Jonathan] Greenert told students of the National Defense College of the Philippines in response to a question about a hypothetical Chinese occupation of one of the disputed Spratly Islands.
"I don't know what that help would be specifically. I mean, we have an obligation because we have a treaty. But, I don't know in what capacity that help is."
Well that's a big deal. It seems like it has been a long time since we've been that explicit in our alliance terms. And we did nothing about Scarborough Shoal.
But Manila did nothing about Scarborough Shoal, too.
I've long figured that we didn't want to fight China instead of the Philippines defending their territory, and that we want the Philippines to have the ability to fight a small battle on their own.
Our alliance would be mainly to help the Philippines win that small fight and (with Japan) to deter China from escalating the battle and overwhelming the Filipino forces.
So the Philippines must have made enough progress on arming up and in giving us access to bases in the Philippines so we can help the Philippines or deploy there.
UPDATE: A new agreement to allow more US forces to operate in the Philippines is pending.
And there is this quote from President Aquino that supports my thinking on the situation:
The Philippines also needed to chart its own foreign policy without being dependent on other countries to solve its problems, he said. Manila has sought arbitration by the United Nations on the dueling claims in the South China Sea, a process China has said it does not recognize.
"This is our problem, we are primarily responsible for it," Aquino said of the dispute. "Nobody will champion our rights if we are not able to champion our rights first."
Yes. We aren't saying the Philippines needs to win a war on their own. But they do need to be able to fight a battle. They need to champion their rights first.
And if the battle is small enough, there is no reason that the Philippines couldn't win that fight, with America (and Japan) standing behind them to deter escalation by China or join the fight to win that escalated battle.