Thanks to a position paper published by Congressman Roilo Golez, the term "area denial" has entered mainstream Philippine social media discussions about tensions with China and territorial threats in the West Philippine Sea. But what exactly is "Sea Denial"? To fully appreciate that mission, one must also understand the super-set mission: "Sea Control".
The following quotations were initially collected for the following discussion on the Timawa.net forum: Sea Control vs Sea Denial: Why small boats aren't enough and provide an easy-to-follow layman's guide to understanding these two concepts.
From an online excerpt of the book The Influence of Sea Power on History: 1600-1783, Boston: Little, Brown and Co, 1896 by Mahan, A. T. comes the following concise distinction between control and denial
Sea denial. Sea denial, or commerce-destroying, provides a means for harrying and tiring an enemy. It may be a means to avoid losing a war. It may cause "great individual injury and discontent". But by itself, a sea denial strategy is not a war-winning one. Nor is it a particularly deterring strategy.
Sea Control. Sea control means, fundamentally, the ability to carry your, and your allies', commerce across the seas and to provide the means to project force upon a hostile, distant shore. A sea controller must limit the sea denial capabilities of the enemy. To quote the Prophet again, "... when a question arises of control over distant regions, ... it must ultimately be decided by naval power, ..., which represents the communications that form so prominent a feature in all strategy."
Between the two strategies, sea denial remains the lowest hanging fruit. Expensive capital ships are principal means of exercising Sea Control and is therefore often beyond the resources of most maritime nations. Even China initially started with this strategy as related by Hugh White, a professor of strategic studies at ANU. The paper not only points out China's approach, but affirms the limitations of this strategy as explained above by Mahan
The Chinese have long understood that America's sea control in the western Pacific has been the military foundation of its strategic primacy in Asia, and that the US Navy's carriers are the key. They have therefore focused the formidable expansion of their naval and air forces over the past 20 years on trying to deprive the US of sea control by developing their capacity to sink American carriers. In this they appear to have been strikingly successful, to the point that US military leaders now acknowledge that their sea control in the western Pacific is slipping away.
But for China, depriving America of sea control is not the same as acquiring it themselves. Its naval strategy has focused on the much more limited aim that strategists call ''sea denial'': the ability to attack an adversary's ships without being able to stop them attacking yours. These days, sea denial can be achieved without putting ships to sea, because land-based aircraft, long-range missiles and submarines can sink ships much more cost-effectively than other ships can. This is what China has done.
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The central fact of modern naval warfare - which the Chinese grasp as well as anyone - is that sea denial is relatively easy to achieve, but control is extremely hard. We seem to be entering an era in which many countries can achieve sea denial where it matters to them most, but none can achieve sea control against any serious adversary.
The key take away from White's thesis is the multi-dimensional nature of the strategy. To enable its own sea denial capability, the AFP needs to make investments in the airborne, maritime, and land-based systems listed above. The Philippine Navy currently has an ongoing acquisition project for brand new Frigates with explicit, albeit limited, Anti-Air, Anti-Surface, and Anti-Submarine Warfare capability. The Philippine Army is moving ahead with studies to acquire land-based Anti-Ship Missile systems. The Philippine Air Force is pursuing a variety of patrol and surface attack aircraft projects. All these efforts, as of writing, remain works-in-progress and their successful and timely completion is hardly assured.
While it is very unlikely that the Philippines will ever be able to make significant headway into sea control on its own, a sea-denial build-up will still put it in a better position to keep cadence with its allies. A coalition of countries with individual sea denial capabilities can approach sea control capability more effectively together than they could alone. A concerted effort to deploy sea-control-compatible assets, would also demonstrate the Philippines' willingness to participate in an allied effort at sea control and establish its status as a reliable partner in such an allied effort, even if such assets can only maintain a tenuous presence in our EEZ when viewed in isolation.