Deplorable though the water cannonading by two China Coast Guard ships of a Filipino resupply boat sailing toward Ayungin Shoal was, China thereafter actually lost a crucial tactical advantage.

Counterintuitive as it may sound, but with the CCG deliberately using “disproportionate force” against a helpless wooden Filipino vessel, China set aside one crucial legal cover for her much-derided gray zone tactics.

To begin understanding how important that legal cover is, it is relevant to first know that China purposely insists that any robust measures against the CCG and the pesky Chinese maritime militia mean using “disproportionate measures” against civilian vessels.

But last week’s deliberate water cannonade by the CCG on the Philippine military-chartered civilian resupply boat Unaizah May 4 effectively paints China as the one using “disproportionate measures” against civilian vessels.

The internationally publicized water cannon attacks are conclusive evidence of China’s embarrassing masquerade as the victim instead of the overbearing bully she really is.

While the attack, which injured four Filipino Navy personnel on board the Unaizah May 4, signals a nerve-wracking escalation of the conflict with China, the tactical advantage nonetheless now lies with the Philippines’ security officials.

It is possible that the latest attack signals China’s dangerous transition from using grey zone tactics to outright black-and-white aggression. But we must await further developments.

Nonetheless, our security officials’ newly won tactical advantage could allow them to deal freely with China’s grey zone tactics, giving them a free hand to cook up possible “robust and determined” measures without having to face legal or moral constraints.

“Robust measures,” in fact, is the larger context by which the Department of Foreign Affairs’ unequivocal demand last Tuesday that Beijing orders all Chinese vessels to leave Ayungin Shoal should be taken.

Such a resolute public demand regarding a WPS feature clearly belonging to the Philippines is probably the government’s first move.

If the DFA’s demand seems quixotic — particularly to perverted pro-China Filipinos committing borderline treason — it nonetheless sets in motion any future robust measures security officials may undertake which hypocritical China can’t possibly counter or complain about later on.

This is not to say, however, that the country hasn’t already undertaken robust measures. Deliberately publicizing Chinese coercion, which successfully put China on the defensive, is already a robust and innovative measure.

Anyway, one possible future robust measure is for the country to take a page from China’s playbook and deploy the Philippines’ maritime militia.

As is known by now, China’s maritime militia is a critical tool in Beijing’s grey zone tactics, not only in the WPS but the entire South China Sea.

Supposedly to secure Chinese maritime militia vessels is a convenient pretext for the CCG’s presence in the WPS, security analysts point out.

Having a Filipino maritime militia isn’t far-fetched. Australian think tank Lowley Institute believes our security officials are already contemplating one following Vietnam’s deployment of its own.

Hanoi and Manila are currently the main targets of Chinese coercion. There are also indications of warming international support for the formation of such maritime militias.

Still, a Filipino maritime militia may not be possible at this time since there are still legal and operational difficulties.

But this doesn’t preclude the possibility of the Philippine Coast Guard blocking or harassing Chinese maritime militia vessels at Ayungin Shoal. China can’t possibly object to such actions now since she harassed us first.

Still, whatever happens, it must be emphasized that any robust actions — short of a shooting war — should be taken with the strategic intention of strengthening the country’s resilience against China’s grey zone tactics.

The Lowley Institute says China “often hesitates to apply such grey zone tactics against more capable targets like Japan and India, which signals that Beijing will adjust its behavior towards a more cooperative direction once it encounters a robust and determined response.”