Taiwan’s New Rules of Engagement

In July 2024, Taiwan’s military released to the public its rules of engagement (ROE) prior to testing their effectiveness in the annual Han Kuang exercises, which took place on July 22-26. Taiwan developed the ROE in 2017 and revised them in 2023 as the People’s Republic of China (PRC) increased the pace and scale of aerial incursions into Taiwan’s air defense identification zone, and against the backdrop of increased naval activity around the island. Although these ROE were prepared for internal distribution, their public release in the form of a portable card gives us a glimpse of Taiwan’s preliminary legal assessment of the situation in the event of a conflict.

Since its establishment, the PRC has maintained the goal of “reunification” and has reiterated that, in its pursuit of this goal, it would not rule out the use of force against Taiwan. The PRC’s resolve is firmly established across various policy papers, legislation, and other official statements. While cross-strait relations have seen highs and lows over the past decades, heightened tensions have been evident after the 2016 presidential election, in which Taiwan voted former President Tsai Ing-wen of the Democratic Progressive Party (DPP) into office. In the eyes of the PRC, the DPP represents a separatist movement seeking Taiwanese independence, and other States’ support for Taiwan has been perceived as external interference obstructing China’s reunification.

In an effort to increase pressure on Taiwan, the PRC has adopted various tactics through diplomatic, economic, and other channels. The PRC’s increasingly coercive measures, including military activities around Taiwan, have garnered international attention. In particular, the military drills conducted by the PRC in August 2022 after then-U.S. House Speaker Nancy Pelosi’s visit to Taiwan, and those in April 2023 after the incumbent President Tsai’s meeting with then-U.S. House Speaker Kevin McCarthy, have been described as a “significant escalation” and “aggressive military activity,” and resulted in calls for maintaining the status quo. Nevertheless, after Tawain elected another DPP candidate who took office in May 2024, the PRC has maintained its aggressive approach by imposing diplomatic isolation, economic pressure, and military threats.

Against this backdrop, Taiwan released its revised ROE to the public. This post offers our thoughts on the utility of the Taiwanese military’s ROE, especially whether they are fit for purpose in light of some of the likely scenarios for a PRC military incursion.

The Text of the Rules of Engagement

For the benefit of English-speaking readership, we provide an unofficial English translation of the text of the ROE below the front and back copy of the original card. One side of the card shows what soldiers can or should do (the right to self-defense, lawful targets, individuals or objects subject to protection), while the other side enumerates four law of armed conflict (LOAC) principles (military necessity, distinction, proportionality, unnecessary suffering) and eight special notes on what soldiers are prohibited from doing.

English Translation:

• You have the right to self-defense by force.

• You should complete your mission lawfully, in accordance with orders of the commander.

1. Against whom you can launch an attack:

• Combatants, commanders, facilities, weapon systems, and equipment of the enemy (as declared by the ROC Armed Forces) are lawful targets of attack. All lawful uses of force can be employed in hostilities until enemy troops are eliminated, destroyed or arrested. Before attacks are launched against the enemy, the purported target must be clearly identified as a legitimate military objective.

2. In addition to the enemy troops, you can engage in hostilities against:

• Those who display clear hostile acts or intentions

3. For whom you can use force to protect:

• Yourself and all members of the ROC Armed Forces

• Designated key infrastructure

• Prisoners of war and detainees

• International organizations, non-governmental organizations, and volunteers assisting humanitarian relief.

4. The troop’s mission-specific rules of engagement:

• To be formulated in accordance with the nature of the unit, the mission, and the specific tasks assigned by the superior.

English Translation:

Humanitarian rules still must be obeyed in armed conflicts.

1. Military necessity: You can employ all necessary means not prohibited by the law of armed conflict to quickly and effectively defeat the enemy forces. Military objectives are limited to those objects which by their nature, location, purpose or use make an effective contribution to military action and an attack against which, in the circumstances ruling at the time, offers a definite military advantage.

2. Principle of distinction (A distinction must be made as you use force.):

• Combatants and non-combatants.

• Military objectives and protected premises/property (e.g., schools and key infrastructure).

3. Principle of proportionality: Incidental civilian damage must not exceed the concrete and direct military advantage anticipated.*

• You must take all feasible precautions to protect civilians and civilian objects.

• Before launching an attack, you must warn civilians in advance to evacuate, unless circumstances do not permit.

4. Humanity/unnecessary suffering: The intentional use of weapons which cause unnecessary suffering is prohibited.

Special Notes
1. Attacks against civilians or civilian objects are prohibited. 2. Indiscriminate attacks are prohibited. 3. Attacks against persons hors de combat or combatants who have surrendered are prohibited. 4. Attacks against or damage to medical personnel, facilities, equipment, or vehicles is prohibited.	5. Attacks against or damage to objects indispensable to the survival of civilians are prohibited. 6. Attacks causing large-scale, long-term, and severe damage to the natural environment are prohibited. 7. Plunder of civilian property is prohibited. 8. If you find any violation of the law of armed conflict by our troops or the enemy troops, you must report it immediately.

[*The literal translation of the sentence reads: “Incidental damage caused by an attack against civilians must not exceed the concrete and direct military advantage anticipated.” But see our commentary below as to why we adjusted the translation.]

Jus ad Bellum v. Jus in Bello

Although ROE are meant to provide operational guidance for troops, Taiwan’s revised ROE card appears to serve dual purposes: an endorsement of the right to use force (jus ad bellum); and the regulation of the conduct of hostilities (jus in bello). The jus ad bellum is a body of international law that regulates the legal justification for the use of force in international relations, dictating—in principle—the legitimacy of political leaders’ decision to go to war. By contrast, the jus in bello regulates how military forces may conduct hostilities in the course of war. The latter rules are often distilled into ROE (see for example the Newport Rules of Engagement Handbook, part I, para. 5) together with mission-specific policy constraints demanded by the political imperatives at the time.

The ad bellum element is implicit in the first line of the card endorsing the right to use force in self-defense. There is nothing unusual about including the right of self-defense in modern ROE as an authorization for taking appropriate action to defend the commander’s unit and other forces in the vicinity. Indeed, the reference to self-defense has been standardized in the peacetime ROE for all U.S. forces since the 1980s, as the circumstances in which U.S. soldiers may initiate or continue combat engagements. The idea derives from the imperative that unit commanders must face when deployed in an uncertain situation, where a hostile act or intent is directed against them. It is the same imperative that underpins the revised ROE card as reflected in the following statement made by Taiwan’s Ministry of National Defense: “[I]f enemy aircraft or ships invade our airspace and territorial waters and cannot be removed after identification, interception, broadcasting, and eviction operations based on the country’s absolute sovereignty over the territory, first-line commanders are legally authorized to take due action to remove the threat.”

Given the risk of surprise attack in a cross-strait conflict, it makes sense to authorize unit commanders a use of force in advance. In the event of a military incursion into Taiwan, the PRC is likely to target communications infrastructure for disruption, with the intention to paralyze or delay political decision-making authorizing military responses. This unit self-defense must be distinguished from the sovereign right of national self-defense in the sense of Article 51 of the UN Charter, noting that the latter’s availability to Taiwan is contentious due to uncertainty regarding its sovereign status.

Alternatively, the ROE’s endorsement of self-defense action envisages scenarios for what the late Yoram Dinstein described as “interceptive self-defense.” According to Dinstein, a State is entitled to exercise its right of self-defense when a hostile course of action is underway to launch an armed attack against it, without waiting to sustain and absorb the actual damage caused as a result (p. 231-33). Taiwan’s Defense Minister Chiu-Kuo-cheng alluded to such a scenario during a legislative hearing about the updated ROE, noting that the military’s definition of a “first shot” by the PRC that triggers action in self-defense has been updated to denote a “first move” involving an infringement of Taiwan’s airspace and territorial waters by the PRC’s military aircraft or vessels. This change, although not obvious from the text of the card, is substantial in that under the updated ROE, unit commanders are authorized to take action in self-defense based on real-time indications on the ground, even prior to PRC attacks reaching Taiwan’s shore.

The expansive use of self-defense authority warrants caution, however. Once a State takes self-defense action, it triggers the application of the jus in bello governing the conduct of hostilities. In a situation of armed conflict, belligerent parties are required to follow the in bello rules as outlined in the remainder of the updated ROE card even when acting on the basis of self-defense. As Gary Corn and John J. Merriam among others have warned, invoking self-defense as a default authority for combat engagements is a slippery slope for the overbroad application of lethal force beyond legally permissible limits imposed under the jus in bello. Taiwanese troops must incorporate the limits of self-defense authority into their training so that soldiers do not conflate the two different use-of-force frameworks.

Law of Armed Conflict v. ROE

Although it is labelled as an “ROE card,” the document is essentially a restatement of basic LOAC rules. We should note, however, that the card contains two possible misunderstandings (or at the least, misstatements) with respect to LOAC. Furthermore, the card does not differentiate between LOAC authorizations, including those most likely to arise if the PRC attempts to invade Taiwan.

As to the ROE card’s misstatements or misunderstandings, the first concerns the way the card describes the proportionality rule. As the literal translation seems to indicate, the card critically misstates the way in which proportionality is assessed, specifically with its reference to “an attack against civilians.” It is possible this is simply a product of imperfect translation or expression, but of course, the rule should be recast to clearly reflect that civilians (and also civilian objects) are not to be made the target of attack. To this end, a better rendering of the rule might be achieved by the option proposed above, or by moving the reference to civilians, for example: “Incidental damage to civilians (or civilian objects) caused by an attack must not . . . .”

The second misstatement is the assertion that a distinction must be made between “[m]ilitary objectives and protected premises/property (e.g., schools and key infrastructure).” Although true, this represents only part of the requirement; a distinction must, of course, be made between military objectives and all civilian objects, not just those objects. Likewise, the rendering of objects as limited to “premises/property” is far too restrictive. The LOAC concept of object is significantly broader than the legal concept of property.

LOAC v. Mission-Specific ROE

As a restatement of basic LOAC rules, this card is not tailored towards any specific mission that Taiwanese troops may conduct in the event of a crisis. To be a useful guide for Taiwanese troops, the ROE card will need to be adjusted to meet the expectations likely to arise under the realistic scenarios in which it will be put for use. To that end, there are potentially useful—but currently missing—LOAC clarifications worth making. Three warrant consideration even at this initial generalized ROE card level.

First, the list of those “Whom you can use force to protect” is expressly limited to “[y]ourself and all members of the ROC Armed Forces; Designated key infrastructure; Prisoners of war and detainees; [and] International organizations, non-governmental organizations, and volunteers assisting humanitarian relief.” Assuming that much fighting will take place on the territory of Taiwan, the missing—and very large—group entitled to protection appears to be Taiwanese civilians generally. There is no prohibition in LOAC relating to attacking the enemy’s targetable forces in order to defend (in this case, one’s own) civilians—indeed, in an invasion scenario, this would likely become a critical mission.

Second, the card provides insufficient guidance on the targetability of civilians taking a direct part in hostilities (CDPH). There are two reasons that warrant some attention for this issue. First, there are longstanding reports of the potential for a PRC “fifth column” to conduct operations in support of an invasion by the People’s Liberation Army. These individuals, if they exist and do engage in hostilities, will clearly present as civilians and not as military force members. This means the indicia to be assessed in determining whether they can be targeted, or whether they are civilians who should not be attacked, are different than those for military forces. This leads then to the second reason some consideration at this general ROE stage might be useful: the complexity of the CDPH indicia. There is a voluminous literature and some public State practice on this question, which is precisely why it warrants early consideration so as to avoid the need to distill and contextualize challenging rules for CDPH on the run when a crisis is already underway.

Coincidentally, an assessment of the CDPH issue may also lead Taiwan’s defense forces to consider the utility of the levée en masse concept in relation to the early stages of resistance to the invasion (if the situation were to be characterized as an international armed conflict when, for example, Taiwan is treated as a recognized belligerent). The reason this may be a useful inquiry is not that it will necessarily be a force multiplier; rather, it is about the importance of having at hand the necessary legal arguments to assert internationally that the adversary must treat these people as prisoners of war if captured.

The third LOAC clarification that warrants consideration relates to the ROE card’s stance on the unlawfulness of making civilian objects the target of attack. This is clearly applicable if Taiwanese troops intend to engage in military operations at sea, in airspace, and within the territory of the PRC. However, given a key theater of operations would likely be Taiwan’s own territory, it may be useful at this early stage to clearly distinguish the situation where the Taiwanese military, on appropriate orders and out of military necessity, is tasked to destroy Taiwanese objects (i.e., those which would be civilian objects to the adversary) in order to, for example, hamper the enemy’s military operations. These destructive operations do not constitute “attacks” within the meaning of LOAC and are not governed by the same rules as targeting operations. Given that this could be a likely mission set for the Taiwanese military in an invasion scenario, it may therefore be worthwhile making this distinction clear so as to avoid the inadvertent and unnecessary confusion created by attempts to apply the military objective test to Taiwan’s “own objects” in this situation.

Concluding Thoughts

The updated ROE card is an indication of Taiwan’s increased level of apprehension about the risk of the PRC taking forcible action and its readiness against that risk. The jus ad bellum aspect of the updated ROE is of particular significance in this respect, clarifying and reinforcing unit commanders’ authority to take action in self-defense based on real-time indications on the ground. Of course, both parties should find a way for amicable solutions without resorting to any forcible action. But an explicit intention to take self-defense action under defined circumstances helps draw a red line and communicate it to avoid the risk of miscalculation and inadvertent escalation of the conflict.

The ROE’s value as operational guidance for Taiwanese troops will further increase by fixing the misstatements or misunderstandings of the law of armed conflict that are evident on the portable card. An accurate understanding of the law is essential to ensure that Taiwanese troops can operate effectively within the bounds of the law and that civilians and civilian objects are spared from the effects of armed conflict. This accurate understanding must be shared among Taiwanese troops as the baseline for mission-specific ROE that are tailored for the likely scenarios in the event of a PRC military incursion.

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Pei-Lun Tsai currently serves as Assistant Professor at Department of Diplomacy, National Chengchi University in Taiwan.

Rob McLaughlin is Professor of International Law at the Australian National Centre for Ocean Resources and Security, Honorary Professor at ANU, and a Senior Fellow at the Stockton Centre for International Law at the US Naval War College. 

Hitoshi Nasu is a Professor of Law in the Department of Law at the United States Military Academy.

 

 

 

 

Photo credit: Office of the President, Republic of China (Taiwan); Taiwan military