Taiwan’s new official defense guideline (防衛固守、重層嚇阻) has been translated by the local media as “solid defense and multi-layered deterrence.” The focus of this article is to analyze the new guideline at the conceptual, rather than operational or implementation level. While the new guideline has been criticized by various Taiwanese legislators as being too vague, Taiwan’s Ministry of Defense should get credit for trying to be creative with this new wording. The guideline, however, is conceptually backwards. The reality is that defense can be multi-layered, but not deterrence. On a practical, operational level, however, the change in the guideline may reflect how Taiwan is becoming more transparent in that its capabilities go beyond just striking amphibious targets invading Taiwan to the perceived necessity of striking more distant targets.
From Porcupine to Archer
At the very least, the new guideline’s title connotes looking beyond the previous approach. The earlier and seemingly softer approach was along the lines of Naval War College Professor Bill Murray’s recommendation that Taiwan adopt a “porcupine strategy”—essentially to strike the tip of the PRC military spear if it initiates a conflict with Taiwan. As Project 2049 Institute analyst Ian Easton pointed out during a recent GTI defense seminar, the three main scenarios in the literature about the PRC’s military options toward Taiwan, in order of increasing severity include: blockade and embargo, targeted decapitation strikes against leadership and the military, and amphibious invasion. A more defensively oriented porcupine strategy would involve striking only the assets at the front lines of an attack, like amphibious assault vehicles as they approach Taiwan’s shores, or intercepting missiles in the air in post-apogee and within the final descent phase.
However, the term “multi-layered deterrence” can appear to eschew a short-range defensive approach, embodying a new and more controversial defense policy focus of striking People’s Republic of China (PRC) targets on the mainland. This new “multi-layered” approach overtly adjusts policy to hit targets earlier and further away from Taiwan. Taiwan Defense Minister Feng Shih-kuan (馮世寬) made news headlines on March 16, when he delivered Taiwan’s new Quadrennial Defense Review (QDR) to the Legislative Yuan and confirmed for the first time ever that Taiwan’s indigenous missiles could target military bases in the PRC. Between what is written in Taiwan’s newly-released QDR, and the Legislative Yuan session, it appears that Taiwan endeavors to acquire or develop fifth generation fighter aircraft, like the F-35 with vertical take-off and landing. It also aspires to develop indigenous attack submarines, improve air defense systems with mobile launchers, upgrade surface naval combatants, deploy smart sea mines, create a fleet of unmanned aerial vehicles (UAVs), and establish a new cyber warfare unit. Many of these new capabilities are more long range than Taiwan’s previously publicized approach. Few concerns would arise if one of Taiwan’s Patriot PAC-3 missiles intercepted an incoming bogey in the air above Taiwan’s territory, but the prospect of Taiwan striking PRC military bases on the mainland would almost certainly concern Taiwan’s neighbors and the United States, not the least because it could escalate toward war.
The reason Taiwan’s long-range missile capabilities could be a policy concern for the United States and others is due to the possibility of a regional crisis. International relations scholars Tom Christensen and Jack Snyder (1990) called this the “chain ganging” effect among cooperative partners that pull one another into crises (though technically their research focus is between allies, and Taiwan is no longer a US defense treaty ally). However, Easton also said that he was puzzled at the media’s surprise that Taiwan could target the PRC, since striking PRC targets has been part of Taiwan’s defense mission since 1962, and the United States expected this of Taiwan when they were defense allies throughout the 1950s to 1970s. He noted that the only way the United States could have reasonable expectations for Taiwan to forego strike capabilities against the PRC is if the US included Taiwan within its defense periphery as a formal defense ally, and under the US’ nuclear umbrella. Otherwise, Taiwan needs to protect itself and ensure its top national interest, which is to survive.
To be fair, American Enterprise Institute fellow Michael Mazza helpfully pointed out at the same GTI seminar that it is hard to imagine that Taiwan would proactively launch a preemptive strike against the PRC. If Taiwan were to target bases in the PRC, then it is more likely to have been after Taiwan was already attacked, meaning that the conflict was already started by the other side. At that point, striking back at distant land targets outside of Taiwan’s territory would be justifiable.
Why Defense is Layered
A layered defense approach is optimal when engaging incoming targets. For example, in general terms, if there is an incoming missile, at over 100 miles away it can first be intercepted with SM-3 or THAAD missiles (though Taiwan does not possess either of these), then at a closer range Patriot PAC-3 missiles could be used. If the missile is even closer and approaching a naval vessel, for example, then a CIWS close-in weapons system could be used for defense. CIWS is a Gatling gun with a multi-million dollar fire control that sprays a wall of lead at the incoming bogey and disintegrates it in the last hundreds of feet. In this way, the defense has many levels, like peeling back the layers of an onion.
There are a variety of systems within Taiwan’s arsenal that take a layered approach to defend against incoming attack. Patriot PAC-3 surface-to-air missiles only intercept incoming missiles, and do not have surface-to-surface capability to strike land targets. Osprey mine hunting vessels inherently lack long-range strike mission and capability. Javelin missiles are short-range, and are most effective against amphibious assault. Apache attack helicopters would fend off amphibious assault, and take a short-range, defensive rather than long-range approach, as long as the helicopters are flown within the Taiwan side of the Taiwan Strait midline. The same defense against amphibious assault applies to Taiwan’s F-16 aircraft, Taiwan’s F-CK indigenous fighter aircraft, Sky Bow indigenous surface to air missiles, Clouded Leopard Armored Vehicles and even submarines–if they stay within Taiwan’s territory, seas and airspace.
Why Deterrence Cannot Be Layered
In contrast, deterrence cannot be layered; on the contrary, the definition of “deter” is to prevent an adversary from taking some action, meaning they that will think twice about whether the benefit is worth the massive cost. Taiwan military expert Mei Fu-shin (梅復興) made the astute observation: “Deterrence cannot be layered because you either have it or you don’t.” The other side either attacks or it does not. Deterrence can be strengthened and it can be “robust” (for example, the US nuclear triad is survivable against attack, and therefore robust), but technically it cannot be layered.
With this in mind, Taiwan’s systems that take a more long range deterrent posture include aspects of its controversial Brave Wind Hsiung Feng (雄風) series of missiles with long range and surface to surface capabilities, or any naval vessels or submarines that are capable of launching Hsiung Feng missiles beyond Taiwan’s territory and airspace (as with the recent misfire incident), along with fighter aircraft and attack helicopters if they venture beyond Taiwan’s territory.
In conclusion, it is likely that “layered deterrence” is political justification to publicly take up longstanding recommendations for Taiwan to have a more forward-leaning operational approach, capable of striking targets both near and far, and to be more transparent about such efforts. Taiwan now officially takes PRC mainland military land assets into account in their calculations. According to Mazza, such capabilities raise the costs for the PRC, since the people of the PRC will be more unsettled by a conflict closer to home, rather than one that is far away. Nonetheless, at a conceptual level, and as mentioned earlier, deterrence is still technically a binary yes or no. Taiwan has it or it does not; it is not a matter of degree.
The main point: Taiwan’s new “solid defense and multi-layered deterrence” defense guideline reflects greater transparency in its missile system capabilities, and in the new operational priorities of the Tsai Administration, but unfortunately contains shortcomings as a theoretical concept.
 Note that the translation used by the media was selected in the absence of an official English version of the QDR released at the time of this publication.
 In this view, previous official Taiwan defense policy makes more conceptual and logical sense: “Solid defense and effective deterrence” (防衛固守、有效嚇阻).
 It should be noted that defense analysts studying Taiwan have been aware of such capabilities for quite some time.
 Thomas J. Christensen and Jack Snyder, “Chain Gangs and Passed Bucks: Predicting Alliance Patterns in Multipolarity,” International Organization 44, No. 2 (Spring, 1990), 137-168, https://www.jstor.org/stable/2706792.
 Discussion with the author, April 3, 2017.