Major, global wars are rare occurrences, and in many people’s memory, there are probably only two real world wars. This of course, is not to deny that wars still break out frequently. According to incomplete statistics, from the end of World War II to 2001, there were 248 armed conflicts in 153 regions. It is therefore, a normal state of affairs for wars and conflicts to take place, and indeed in contrast it is abnormal if wars do not happen at all. Therefore, the study of war and peace has always been a main component of geopolitics.

All-Domain Battle & Multi-Domain Battle

Some of the most important and popular war theories now are "all-domain battle" and "multi-domain battle".

Multi-domain battle was first introduced in 2016 as a U.S. Army’s battle concept by Chief of Staff of the Army, General Mark A. Milley and then by Mark Esper, the Secretary of the Army during Trump’s Administration.

The primary goal of the original "multi-domain battle" is to counter China and Russia's Anti Access/Area Denial (A2/AD). What distinguishes it from joint operations is that, army services can share information, synchronize operations in different combat domains seamlessly. Due to the continuous integration of space, network, electromagnetic spectrum, and information environments, the future of joint operation shows clear globalized feature, and its battle space will be far more than any national army's battle function range. This is a battle support system for seamlessly fused information advantages. Of course, the existence and division of these battle domains is merely the understanding of the current operational needs, the actual operation where the battle-related domains can be much larger, and can even include all levels of society, such as population and news.

Since then, "multi-domain battle" has moved towards the concept of "all-domain battle". This is a process of war efficiency framework, which combines the new combat concepts of various military species. Former chairman of the Joint Chiefs of Staff (JCS) General Joseph Dunford, first proposed the Global Force Management (GFM) concept, and later added with the concept of “global fires”, which includes weapons both physical (missiles) and non-physical (cyber-attacks) that could be launched from outside a theater of war to have effects within it.

Overall, the concept of "all-domain battle" is the core of Joint All-Domain Command & Control (JADC2) as the core, integrating into a new battle domain, and makes full use of the domain in battle means and choices. JADC2 is coordinated by the Chief of Staff and led by the Air Force, to ensure that all field platform sharing information enables the U.S. military to make the most effective and fatal actions by implementing sensors, communication, and data integration. Such is the “all-domain warfare” that now appears frequently in the media.

The U.S. FY 2021 Defense Budget shows that the U.S. military focuses on the concept of "all-domain battle", in which the modernization of nuclear, missile defense, space, network, air force, navy, army, precise guidance weapons, orientation weapons and high ultrasound weapons, and artificial intelligence, are upgraded to improve the combat capabilities.

It is worth noting that there are two problems in all-domain battles. First, the cost is high and requires cutting-edge technology, making it a battle mode only suitable for the United States. Second, the military ability of the all-domain battles is actually facing world war, not smaller scale local wars which are the wars that appear most frequently.

If the war process is developed towards all-domain battles, then it is not far from world war. Therefore, it should be noted that all-domain warfare is typically a major power’s strategy and option. Most countries will be unable to develop an all-domain warfare, and these including Japan and Europe.

Partial-Domain Warfare and Geopolitical Warfare

Partial-domain warfare is another option other than all-domain warfare, where in definition, the former is relative to the latter. Partial-domain warfare is based on the efficiency and cost of warfare, conducted in a single domain or multi-domain with limited and efficient combat equipment.

There are two features of partial-domain warfare. The first is the emphasis on battle efficiency. This means that battle domain itself must be optimized where key areas of efficiency must be highlighted, yet it would not achieve comprehensive reinforcement and superiority in all battle domains from air to land, as such warfare mode usually means extremely high costs. The second feature is the emphasis on war within the framework of geopolitics. Geopolitical warfare is defined as warfare that focuses on achieving geopolitical goals. The scope is then limited, confined within a country or several countries. That said, the boundary of the influence of the war does exist, and its very own nature determines the outcome of the war. Therefore, this type of war is an extremely obvious political war.

It must be pointed out that the use of all-domain warfare model and battle method to achieve the purpose of partial-domain warfare is completely inefficient economically, and therefore not sustainable. Even a powerful country like the United States is highly likely to fail, and this is determined by the overall social cost.

Compared with all-domain warfare, partial-domain warfare is more efficient and relatively more limited. Within this, the choice of key domain is crucial, and this will determine the advantages in the partial-domain warfare. We have previously noted that “the outcome of war is determined at office desk[1]”, and this strategic idea is also applicable to the selection of key domains. If the selection of key domain is correct, the victory of modern geopolitical wars can be ensured, and there will be no failures such as out-of-control on the battlefield or embarrassing evacuation.

Partial-Domain Warfare and Technological Progress

The advantage of partial-domain warfare depends on technological progress, especially those in key domains. Gaining victory in key domains instead of all domains is of decisive significance for winning a geopolitical war. For example, in the Vietnam War, the main factors of victory in Vietnam were its population and cost. Although North Vietnam was far inferior to the United States in terms of all-domain capabilities, it gained advantages in key areas. The constant supply of manpower and low costs[2] gave North Vietnam and edge to defeat the United States and forced it to withdraw.

The victory of partial-domain warfare is closely related to technological progress. The biggest technological advancement in modern partial-domain warfare is the large-scale use of unmanned aerial vehicles (UAVs), especially low-cost ones (below US$ 7 million per unit)[3]. Although in the future directed energy weapons may improve UAV defense to a new level, if they combine well with stealth fighters, they have the potential to become the main force in warfare. Since Iran hijacked American UAV in 2007, the use of UAVs in the Middle East has become increasingly common again, which means that the security channels and electronic interference issues related to UAV control have been resolved to a certain extent. As for the UAV’s long-range attack ammunition, UAVs can avoid ground air defense fire while performing battlefield defilade missions on a large scale to achieve battlefield control[4].

The effective use of UAVs and large-scale attacks, in conjunction with stealth fighters, are important means of partial-domain warfare. The maximum effectiveness of stealth fighters can win absolute or relative air dominance[5], and fully suppress ground defense weapons, while the large-scale use of UAVs can project a large amount of firepower to the ground and gain the dominance of war. The advancement of UAVs and stealth fighters has created conditions for the realization of partial-domain warfare, making it the most promising mode of domain warfare. Through the continuous and effective attacks, UAVs can control and destroy targets in the theater, forcing the enemy to surrender and negotiate, so as to achieve geopolitical goals. In this sense, because it does not use ground armed forces to achieve large-scale intervention and occupation, it is conducive to rapid action. That said, the final result of the partial-domain warfare model of UAVs and stealth fighters can only be a political solution, not complete military elimination. This is determined by the nature of partial-domain and geopolitical warfare.

In partial-domain warfare, the coordination of information warfare and electronic warfare is vital. On the one hand, this itself is an important suppressive force that can make enemy fighters and ground air defense equipment unable to function; on the other hand, information and electronic warfare are also key areas that can be selected in partial-domain warfare, which may decide the failure or victory of the warfare participant.

Therefore, judging from the technological progress of partial-domain warfare, the most promising technical equipment plan is this: stealth fighter + information warfare + electronic warfare —> air domination —> UAV attack —> political solution. It is the cheapest and most efficient solution to geopolitical warfare in reality. In such a battle mode of local warfare, the acquisition of air domination is the most important assault direction of the air force. Once air domination is obtained, ground defense weapons will be completely suppressed. The remaining tasks are mainly precision and non-precision strikes.

Assessment of War Practices

There are several existing examples of wars that can provide some reference points and verification for partial-domain warfare.

UAVs have been used to some extent in the Afghanistan war, but they have not been used on a large scale or become a major force on the battlefield. The reason for this is that American military UAVs are still too expensive. In the future, if the U.S. military can mass-produce cheap UAVs and load them with of low-cost ammunition, they will certainly become the most effective intervention weapons.

The war in Afghanistan was actually a war for which the U.S. military was not adequately prepared. The U.S. military's weapon systems and geo-strategy are not prepared just for partial-domain warfare, their war systems have always been prepared for all-domain warfare. As a result, the United States has frequently failed on important battlefields of the world.

In the Middle East on the other hand, American UAVs also show significant activities, yet they are more well-known in killing Qasem Soleimani[6], the leader of the Iranian armed forces, though they were rarely deployed in other areas. The reason for this may be that the cost of UAVs in the United States is too high, which restricts their use.

It is worth noting that low-cost reconnaissance and attack UAVs are an effective restraint weapon system for guerrilla warfare. Because the basic model of guerrilla warfare is concealment, maneuvering and base areas, UAV area control capability can kill key leaders, attack the command system, control traffic arteries, and eliminate technical equipment, making it difficult for the guerrillas to assemble and get supplies. Therefore, the basic mode of partial-domain warfare with UAVs as the core will cover the entire battlefield and give full play to its technological advantages, thus having a huge possibility of defeating guerrilla tactics.

Conclusion

In researching war and peace, a long-standing concept is that once a war has occurred, victory must be won regardless of cost. Therefore, cost is often not placed under consideration. This is a wrong theory in the long-term war practice of various countries in the world. From a long-term perspective, the cost-effectiveness ratio of war should indeed be considered by any country under most war conditions, otherwise failure will be inevitable.

Because of the increasingly expensive technology and equipment, the defeat of almost all modern wars, including World War II initiated by Adolf Hitler, were not caused by military but rather by high cost. Such is the importance of the cost-effectiveness of war and the geopolitical significance of partial-domain warfare.