The Changing Nature of the Three-Block War

Adopting a multidimensional mindset demands a mentality shift around the way that the modern US military is trained and employed.
Kevin Johnston, Amelia Snyder, General Charles Krulak, Krulak three block war, US military news, US military operations, US military training of allies, US withdrawal from Afghanistan, US support for Ukraine, US cyber capability

© Aleksandar Malivuk / Shutterstock

July 06, 2021 10:02 EDT

While codified as the future fight for the Marine Corps in General Charles Krulak’s prescient 1999 essay, “The Three Block War,” offensive military actions, civil-military operations and humanitarian aid are not unique to the Marines. Given that all branches of the US military often complete the same missions in the same operating environment, General Krulak accurately predicted that the armed forces would face simultaneous combat, peacekeeping and humanitarian operations in 21st-century warfare.

Recent military conflicts illustrated two additional essential tasks: training allies and enhancing cybersecurity. Building up the capabilities of military partners quickly became a primary concern for American forces seeking to turn over responsibility to local personnel and improve alliances with peer and near-peer nations. The rise of smart devices and social media platforms created an atmosphere in which cybersecurity defense became crucial to force protection, both at home and abroad, adding a new dimension to every block of warfare. 

Has the US Always Been at War?


The pervasive requirement for training allies and ensuring cybersecurity have expanded General Krulak’s three-block war into new dimensions. Service members execute these actions as part of offensive actions, peacekeeping operations or humanitarian missions. Adopting a multidimensional mindset emphasizes their critical role across each of the three blocks and demands a mentality shift around the way that the modern US military is trained and employed. 


Training allied forces became a critical component of strategic victory at the turn of the century. For the past 20 years, US service members have trained with allied forces in operations and exercises around the world. The goals of these sessions vary depending on the location and threat. No matter the partners, training allied militaries remains a key mission necessary for enhancing security around the world and repelling threats from organizations the United States opposes. Therefore, training should be considered a basic function of the US military.

Success in unconventional warfare does not hinge on traditional battlefield metrics but on the ability of the allied nation to maintain its own security and to leverage allied strengths to grow internal capabilities. Promoting training as a key function of the army brings this mindset to the forefront. During the war in Afghanistan, the United States provided security in the host nation while simultaneously training its new army. This contrasted with the Bosnian Train and Equip Program, where the American military equipped and trained an existing organization. In Afghanistan, the United States had to build a military from scratch.

In January 2002, several months after the beginning of Operation Enduring Freedom, Afghan President Hamid Karzai and US President George W. Bush announced the creation of an Afghan military, which would receive training from the United States. From 2002 to 2014, US forces trained 194,000 Afghan troops, in an attempt to give Kabul the ability to fight anti-government forces.

At the end of 2014, the United States ended Operation Enduring Freedom and began Operation Freedom’s Sentinel. In keeping with the belief that American victory hinges on the success of the indigenous forces, Freedom’s Sentinel laid out two objectives, one of which was the training of the Afghan army. In 2019, there were over 14,000 American troops stationed in Afghanistan.

Training local military allies remains one of Washington’s primary methods for victory over the Taliban and other anti-government forces in Afghanistan. With President Biden’s decision to end America’s longest war and US troop withdrawal now in its final stages, the success of this mission will hinge not on the performance of foreign forces but on the performance of the Afghan army when it becomes the sole guarantor of security in the country.      


The conflict in eastern Ukraine saw a different style of unconventional warfare led by America’s allies. Here, the host nation is responsible for its own security but relies on the United States for support to train service members. After the Russian invasion of Crimea in 2014, the United States, United Kingdom and Canada created the Joint Multinational Training Group – Ukraine (JMTG-U)  with “the mission of training, equipping, training center development and doctrinal assistance to the Ukrainian armed forces.”

US and allied service members set up training sites at Khmelnytskyi, Javoriv and Kamyanets-Podilsky. The plan was for up to five battalions to be trained every year. By 2016, the Ukrainian army had 200,000 combat-ready soldiers. Over these years, Ukraine maintained its own security and relied on training from its allies to break the stalemate between nation-states.

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This mission was different from Afghanistan since the United States never took over Ukraine’s defense and worked to improve an existing organization, not create one that did not previously exist. But like in Afghanistan, the ability of American service members to train with allied troops was key to the success of the mission: enabling Ukraine to withstand the separatist insurgency in the Donbas region.

Following the start of JMTG-U, The Ukrainian military was able to prevent the pro-Russian forces from pushing further west, thus making an aspect of the mission a success. In 2020, Russia, Ukraine and the Organization for Security and Cooperation in Europe negotiated a ceasefire in Kyiv. Though there are routinely tactical level violations of the ceasefire, it remains in place at a strategic level.

The longstanding training mission, combined with Ukraine’s desire to hasten its NATO membership, likely means that Ukrainian forces will not have to fight pro-Russian forces unilaterally on a strategic level again. Thus, the only judge of mission success is Ukraine’s ability to guarantee its own security until becoming a NATO member.


The US needs allied support to be successful against peer or near-peer threats, and mutual training allows for the cooperation and integration necessary for victory. In this scenario, the United States does not take sole responsibility for training or security but rather pursues those goals in tandem with an allied military. For instance, the US and the Republic of Korea (ROK) )created the ROK/US Combined Forces Command in 1978, with the mission “to deter, or defeat if necessary, outside aggression against the ROK.” In this alliance, the US and Korean forces share all responsibilities equally and have a binational command structure for headquarters and component commands.

US training with Korean forces is similarly integrated in large-scale military exercises. Ulchi-Freedom Guardian is designed to “enhance ROK-US interoperability by training commanders and staffs from both nations in wartime planning, command and control operations, intelligence, logistics, and personnel procedures required for the successful defense of the Republic of Korea.” Similarly, Key Resolve is meant to help with the “integration of US augmentation forces that would be deployed to the peninsula during war.”

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In both scenarios, the focus is on the two nations working together as peers on training and security. In the event of a conflict, the ability to repel a foreign adversary depends on the United States and its allies being able to overcome an enemy force together while still maintaining the ability to train new service members. Although the US and South Korea came close to fighting side by side multiple times during the Cold War, the most recent scare came in 2017, when President Donald Trump’s “fire and fury” threat prompted North Korea to announce it was examining plans to launch missiles at Guam.

To maintain its dominance during any type of warfare, the United States must prepare all its service members to be able to train with allied forces. In special forces training, Green Beret candidates complete a capstone event known as Robin Sage, where the goal is to train with a local military force to repel an invasion. In this environment, candidates train mock resistance fighters. Mission success is when the resistance fighters are capable of leading training for others in their organizations and conducting operations missions on their own in a fake country called Pineland.

Robin Sage is meant to train service members for an unconventional conflict, but the hallmark feature of having Americans train with an allied nation can be adapted into other training scenarios designed for conventional forces. A US military prepared to train with allies will be able to adapt and win during future conflicts, making training with allied service members a crucial fourth block in the next generation of warfare. 

Tactical Cyber Warfare

The US military has focused on cyber, its related domains and the impacts they can have both abroad and at home. Part of this has been the acknowledgment of the newest war front — information. Since the publication of “The Three Block War,” the scope, scale and investment in cyber warfare increased exponentially as information, and its use and misuse, loomed large in public minds and military planning. By 2004, the military and civilian cybersecurity market was worth $3.5 billion in the United States alone. This expanding market was also tapped by cybercriminals, who collectively stole almost $1 trillion in 2020, prompting additional government and private security spending.

The growing importance of the cyberspace domain and the expansion of the Internet of Things has played a role in this acknowledgment. As more devices become networked and the sophistication of cyber tools grows, hostile actors have more opportunities to execute harmful attacks with augmented publicity and deniability in case of success. In 2019, NATO declared cyber a domain of war, stating: “Allies recognise that cyber-attacks could be as harmful to our societies as a conventional attack. As a result, cyber defense is recognised as part of NATO’s core task of collective defense.” Tactical cyberwarfare’s growing presence and its potential to affect future conflicts illustrate why it is an important dimension in General Krulak’s neighborhood.

The closest example to an official definition of cyberwarfare was proposed by the former US national coordinator for security, infrastructure protection and counterterrorism, Richard A. Clarke. He defines cyberwarfare as “actions by a nation-state to penetrate another nation’s computers or networks for the purposes of causing damage or disruption.” However, this strategic definition is based on the history of cyber warfare and technological limitations.

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The use of cyberspace as a means of exchanging communications is overwhelmingly the most common method at the strategic and operational levels of warfare and is increasingly important in tactical warfare. Advances in computer technology and other personal devices created a new realm of cyber: the tactical level. Harmful actors no longer need to depend on nation-states for funding and access but are capable of executing wide-ranging and crippling attacks as terrorist groups or individuals.

Our current use of cyber warfare is defined as actions within the cyber domain that enable another warfighting function to achieve the commander’s objective. Tactical actions are executed at the division level or below, with approval authority residing at the level of the commanding general. Tactical cyber warfare in this discussion is executable by the military in the operating forces in support of ground forces without requiring support from another service or national agency. This definition brings cyber authority to a lower level than it currently resides at. But this is the level necessary to maintain an expeditionary force capable of acting in a time-dominant environment.

Tactical cyberwarfare presents both potential benefits and pitfalls for the US military. Recognizing cyber’s growing influence, the 2014 US Army’s Strategic Planning Guidance stated the need for cyberspace capabilities that would be joint as well as tactical. This would enable service members to utilize cyberwarfare weapons in a wide range of environments, from local missions supporting combat operations to strategic cyberwarfare actions undertaken by coordinated actions across multiple branches of the military.

Many cyberweapons are only able to be used one time. Once a vulnerability has been exploited, the adversary knows it exists and can monitor for similar intrusions or address the liability. An example is the discovery of Stuxnet, an extremely effective malware targeting industrial control systems that damaged nuclear facilities in Iran. The attack illustrated how cyber weapons are not restricted to computer networks; after the attack, the exploit was patched. This limits future attacks that would have targeted the same software vulnerabilities and has potentially limited future attempts against systems other than computers as now more designers are aware of potential threats.

Onetime use results in tensions over who can approve cyber techniques, since a commander using an offensive cyber capability for one mission may result in future commanders being unable to use that capability. Unlike developing body armor to respond to new types of bullets, the rollout for fixes on networked systems can have quick turnaround times and instantaneous upgrades across a large network. Although these decisions happen far above the tactical level, troops in an operation must understand why some capabilities cannot be used during a mission.

New Dimension

Opposite from the offensive side of cyber operations, Department of Defense Information Network operations exist to maintain the security of US military networks. But just as the US can use cyber as a weapon, its adversaries can as well. Every service member deals with devices that could potentially be exploited through cyber tools. Both military and personal devices are vulnerable to a variety of attacks, from malware to personal identifiable information phishing. In 2018, following the revelation that fitness trackers were showing the location of US service members, the Pentagon banned devices with GPS capability in war zones.

Establishing cyberspace as a new dimension creates a seriousness and intent that do not currently exist. The perils and risks of adversary tactical cyber operations need to be added to the military’s updated training modules. The idea that both friendly and enemy forces can be located and destroyed due to carelessness with everyday devices needs to be imprinted into the minds of service members. These actions need to occur not just when troops deploy but as they train at home.

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Cyber does not lose its utility outside of a hostile environment. In permissive or semi-permissive areas, cyber can be used for outreach, education and mission planning. Public affairs offices ensure coordination with local media outlets, crafting a narrative around troops’ presence and intentions in foreign countries. In addition, cyber actions shape the environments for future operations. Articles such as the Department of Defense’s “Humanitarian Operations Save Lives, Build Goodwill” adjust global perceptions of American troops.

These products, created in cyberspace for global consumption, are rapidly disseminated and obtainable at every level, from decision-makers at the United Nations to the users of internet cafes in developing countries. While cyber can reinforce hard military power, it can be just as useful reinforcing messaging from the United States through soft-power persuasion. As the US military plans and executes operations, cyber should be intentionally utilized from shaping actions to the execution of attacks.

US military operations validated General Krulak’s vision for the future. Knowing how to carry out all three types of engagement, as well as knowing that they may need to rapidly transition between tasks, was vital to the success of unit operations. But there are now more dimensions to the neighborhood.

Training local national forces has already become a mission for US service members. Despite shifting focus at the national level, training and tactical cyberwarfare remain key activities for the US military. Rather than a holdover from counterinsurgency operations, training local national forces is a way to ensure success in a conflict with a great power. As General David Berger stated in his commandant’s planning guidance, “Our wargames have shown that in any great power conflict, our alliances are an essential factor to achieving success.” Entering the fight with allies by our side enables more effective actions and reactions by the US military.

Meanwhile, cyberwarfare offers stunning new possibilities and horrifying new risks. Information that seems innocuous can be turned into a weapon. As the US military prepares to fight in cyberspace at the same time as it conducts operations in a physical environment, it needs to ensure its service members understand how the cyber factor changes operations at home and abroad, expanding conditions in General Krulak’s original three-block war.

Adopting a multi-dimensional mindset prepares the military, including the newest strategic corporals, to act in a complicated world. While the pressures and responsibilities facing our leaders continue to grow, changing mindsets during training and deployment enables service members to see the whole picture and make the right decision, saving lives and accomplishing the mission.

The views expressed in this article are the author’s own and do not necessarily reflect Fair Observer’s editorial policy.

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