During the last few decades, the increasing use of asymmetric and multimodal tactics by terrorists has led anesthesiologists worldwide to analyze and discuss their role in mass casualty scenarios in more depth. Now anesthesiologists must address the new situation of hybrid threats and hybrid warfare. This will have a direct impact on anesthesiology and intensive care, and in the end, the health and well-being of critical patients of all ages. To be able to respond to a hybrid threat efficiently and effectively, it is imperative that anesthesiologists play an early and integral role in mitigation and response planning.

During the last few decades, the increasing use of asymmetric and multimodal tactics by terrorists has led anesthesiologists worldwide to analyze and discuss their role in mass casualty scenarios in more depth.  This is a logical development since anesthesiologists have the core skills to deal with the clinical aftermath of terrorist attacks from the point of injury in the prehospital setting to the emergency department, operating room, and intensive care unit (ICU).  Now, anesthesiologists must address the new challenge of hybrid threats and hybrid warfare, which will have a direct impact on anesthesiology, intensive care, and fundamentally, the health and well-being of critical patients of all ages. Research looking at hybrid warfare and how it impacts health care in general and anesthesiology in particular is extremely sparse. However, the similarities between the multimodal aspects of hybrid warfare and modern-day terrorism enable us to apply some of the lessons learned from the latter to the analysis.

In this article, the authors discuss some of the fundamental principles of hybrid warfare and how they affect individual physicians as well as anesthesiology departments, in addition to strategies that may help with preparedness and mitigate risk to patients, staff, and departments. Another term often used together with the concept of hybrid warfare is the gray zone of conflict, the zone between peace and war without crossing the line of open war. The focus of this article is on the civilian anesthesiologist working in these conditions, in gray zone of conflict, and during hybrid warfare.

There is no internationally accepted definition of hybrid warfare, but it is usually described as a combination of conventional, irregular, and asymmetric strategies deployed in a civilian-dense setting.  In hybrid warfare, combinations of advanced weapons systems are often used, including modalities such as chemical, biologic, radiological, nuclear, and high-yield explosives, in addition to disruptive technologies like drones and cyberterrorism. Disinformation, terrorism, corruption, and criminal behavior are also core pieces of this malicious playbook.  All modalities seen in hybrid warfare may be used in attacking hospitals and healthcare systems—either as a unimodal strategy or more probably in a multimodal and synergistic way (table 1). Furthermore, this threat of compounding attacks has been increased by advances in technology, changes in demographics, and the Great Power Competition between China, Russia, and the United States. Aggressors in conflict settings aim to destabilize governments, community trust, and cohesion, often exploiting the blurred line between war and peace and sowing confusion among the masses.

Table 1.

Modalities of Hybrid Warfare

Modalities of Hybrid Warfare

It is vital to understand that anesthesiologists will most likely be at the epicenter of a hybrid attack. The current war in Ukraine has shown that medical providers are not immune to violence and aggression in hybrid conflicts and may even be intentionally targeted.  This has led to a shift toward smaller, more mobile hospitals and surgical facilities that are often hidden in basements and bunkers instead of being in full view with a prominent red cross in plain sight. The constant threat to health care also affects patient transport and logistics where unconventional transport modalities may be needed, such as the use of unmarked ambulances during this particular conflict. Anesthesiologists currently working in Ukraine describe extreme challenges they face, noting that civilian anesthesia in a hybrid war hot zone is unpredictable and very different from a peacetime environment. The constant threat faced by healthcare facilities and the destruction of supply chains requires anesthesiologists to improvise regarding locations, medications, and equipment. 

Furthermore, the conflict in Ukraine is between near-peer adversaries. Therefore, medical evacuation plans must be managed differently, compared to previous conflicts such as Operation Enduring Freedom and Operation Iraqi Freedom. Allied forces no longer have air superiority. Consequently, air evacuation, which was a core component of the patient movement plan in Operation Enduring Freedom/Operation Iraqi Freedom, is not possible in this current conflict.

Anesthesia providers are a core strategic resource for a nation’s capacity to handle critical events. This may put anesthesia, and the anesthesiologists themselves, in the crosshairs of an aggressor. The roles of anesthesiologists differ around the globe, but their core skills make this physician group an extremely valuable asset in complex and critical situations like mass casualty incidents, terrorist attacks, and pandemics, in addition to the new threat of hybrid warfare. Anesthesiologists play an important role in a wide spectrum of acute care medicine, including the management and resuscitation of critically ill or injured patients, which can span the entire care trajectory from prehospital through to the emergency department, operating room, and ICU. Additionally, they also play a principal role in nonclinical, resource-based decisions. These are all potential roles needed when dealing with the aftermath of a hybrid attack. Several after-action reviews of terror attacks have highlighted the anesthesiologist as a key decision-maker in patient flow, logistical support, patient triage, and advanced care, as demonstrated in terrorist attacks in Oslo, Norway; Paris, France; and London, United Kingdom, which unexpectedly flooded hospitals with civilian casualties. 

Cyberattacks against healthcare providers are increasing, with the U.S. Department of Health and Human Services (Washington, D.C.) registering 679 such events in 2021.  Most attacks and breaches are perpetrated by criminal hackers, but there are also attacks made by state-sponsored groups, like the hacker attack against Boston Children’s Hospital (Boston, Massachusetts) in 2021.  For example, cyberattacks from Russian hackers recently actively targeted U.S. hospitals in response to the support of Ukraine in the current conflict. These attacks fall within the paradigm of hybrid warfare but are also part of gray zone tactics. With our increasing dependence on computer systems and technology in operating rooms, ICUs, and critical care transport, most healthcare systems are extremely vulnerable to cyberattacks. During the last 2 yr, software vulnerabilities that render specific models of anesthesia workstations, ventilators, infusion pumps, and imaging devices susceptible to cyberattacks have been identified. Research has shown that it may be difficult to recognize a cyberattack in critical care environments; there is room for improvement when it comes to training and mitigation.  The effects would be compounded if a cyberattack was launched during a mass casualty incident or in combination with other hybrid threats, the results of which could seriously hinder all aspects of care, from initial response to postoperative care and intensive care. Researchers have also found that hospitals that experienced cyber events were more likely to suffer hospital strain (measured by ICU bed utilization), worse health outcomes, and increased patient mortality.  Chemical, biologic, radiological, nuclear, and high-yield explosives modalities could be used by various rogue groups and state-sponsored actors in a civilian setting and may be used in assassination attempts of political targets as well as mass casualty incidents. This is an area where anesthesiologists offer unique insight due to their familiarity with cholinergic and anticholinergic pharmacology. Furthermore, if respiratory failure is present, definitive airway management and invasive ventilatory support will be needed, an area in which anesthesiologists have the most expertise. All these aspects were present in the Salisbury Novichok nerve agent incident in 2018 in the United Kingdom.  As demonstrated by this event, even a small number of affected people will cause enormous pressure, particularly on intensive care and chemical, biologic, radiological, nuclear, and high-yield explosives experts. 

The constant fear of exposure to COVID-19 since early 2020 has made anesthesiologists experts in using personal protective equipment to reduce the risk of becoming infected. These crucial skills and this knowledge base can be applied to chemical, biologic, radiological, nuclear, and high-yield explosives attacks, making anesthesiologists ideal candidates to serve as consultants in the design of optimal care pathways to minimize risk to patients and other healthcare providers.

Criminality can be a very potent weapon for an adversary; this can include narcoterrorism, counterfeit pharmaceuticals, smuggling of advanced weapons, exploitation of urban gang networks, and socially disruptive behaviors.  In several Western countries, there have been attempts by criminals to breach hospital security when gang members are being treated in the facility. This creates a dangerous situation for staff and other patients, highlighting the need for healthcare target-hardening measures.  The same scenario has been seen during the COVID-19 pandemic when relatives of patients stormed ICUs and attacked physicians. 

Since 2015, there have been greater than 500 terrorist attacks targeting healthcare facilities worldwide. Hospitals and ambulances are soft targets and if attacked can cause major disruption in medical services. While direct attacks on healthcare facilities and staff will impede care and normal function, the indirect effects of terrorist attacks on surrounding communities or nonmedical infrastructure can also have a compounding effect on healthcare delivery.

Terrorism is one of the most important components that make up the challenge posed by hybrid warfare.  From analyzing historical events, we know such attacks will likely take the form of complex, multimodal attacks causing a surge of trauma patients leading to short- and long-term strain on anesthesia and intensive care services. Examples of attacks with high impact on anesthesia services are the Paris, France, attacks in 2015; the Nice, France, truck attack in 2016; and the Utøya, Norway, shooting in 2011, where large numbers of prehospital and in-hospital anesthesiologists were involved in direct care as well as leadership and coordination. Traumatic injuries after terrorist attacks are relatively well-described in the literature, but detailed knowledge about civilian injury patterns in other forms of hybrid warfare is lacking. However, we know that complex multitraumas of all ages are rampant in the current conflict in Ukraine.

Analysis of past terrorist attacks in Norway (Utøya and Oslo), London, Paris, and Boston demonstrates that anesthesiologists have played a crucial role in mitigating the horrifying effects of these events for the entire continuum of a patient’s journey by providing advanced medical decision-making in addition to treating critical patients.

As gatekeepers to the operating rooms and ICUs, it is imperative that anesthesiologists take an active role in disaster planning to provide the most effective care to patients. 

It is important that every anesthesia department establish and practice the execution of a well-designed disaster plan, which should include the response to hybrid threats regardless of the threat’s origin. The degree of violence toward healthcare providers and hospitals will necessitate different strategies for planning and mitigation. Planning for a violent scenario requires cooperation with the police as well as the military, while planning for devastating cyberattacks needs joint situational awareness with the information technology department on how to counter this threat.

It is also important to understand that it is not just the hospital phase and the hospital-based anesthesiologist that can be affected by hybrid threats. The prehospital phase, including patient transport by air ambulance or fixed wing, may be extremely sensitive to disruptive technologies like drones as well as cyberattacks. Public disorder, riots, and protests can seriously affect ground transportation and access to healthcare facilities. The foundation of these plans should be built on an all-hazards approach, but there must be flexibility in the system to adapt to hybrid threats. Depending on the circumstances, anesthesiologists may need to perform their work in unconventional settings, with improvised equipment and nonstandard medications. In hybrid warfare, equipment must be able to be used without connection to computer networks, be portable, and function with a battery power supply. Diagnostic tools like portable ultrasound and point-of-care blood gas analysis as well as basic transport ventilators are well-suited to these environments.

If communications deficiencies occur, organizations must be able to revert to redundant systems. Terrorism-related incidents and cyberattacks have shown that emergency medical services and hospitals can use techniques like Wi-Fi–based communication and satellite radio as well as human runners and paper and pen.  Understanding the subtleties, complexities, and uniqueness of the impact of hybrid attacks on health systems is an important first step in mitigating the risks to patients and communities. As such, the authors suggest that education and training in disaster management, disaster medicine, and counterterrorism medicine should be incorporated into the continuous medical education for anesthesiologists and critical care physicians where such threats exist. Anesthesiologists, regardless of their career phase, need to educate themselves and ensure competency in their role during mass casualty incidents, chemical, biologic, radiological, nuclear, and high-yield explosives events, cyberattacks, violence inside the hospital, and other intentional events. Current anesthesiology residency programs should develop a curriculum and incorporate simulation training to better prepare future generations of anesthesiologists for the key role they will play in these events.

There are currently no best practices for planning, mitigation, and response in health care or anesthesia to hybrid warfare situations, but some of the guidance from the military can be used as a basis and certain available mass casualty planning tool for civilian events and to some extent adaptable.  The North Atlantic Treaty Organization (NATO; Brussels, Belgium) has guidance on how to counter hybrid threats that can be used in a more civilian setting as well.  This may include raising awareness within the own organization of different hybrid threats as well as creating resilience through interorganizational education, training, and exercises. Departments, hospitals, and healthcare organizations must cooperate to create and implement plans together. There is also guidance on a broader level from the European Parliament (Strasbourg, France) suggesting best practices in the whole-of-society approach in countering hybrid threats.  Worldwide cyberattacks and the ongoing situation in Ukraine have shown that regional, national, and international cooperation may be needed to mitigate and counter the effects of hybrid warfare. Some of the lessons learned from the COVID-19 pandemic can be used to aid international cooperation, especially those related to unstable supply chains, lack of adequate equipment, and medication as well as the spread of disinformation.



Hybrid warfare is an increasing multimodal threat to all segments of health care, particularly the various settings where anesthesia and intensive care are provided.

The nature of modern-day threats makes it necessary that anesthesiologists acquire foundational training and education in disaster medicine. Despite typically not being prioritized for participation in mass casualty incident drills (unlike prehospital or emergency medical services and emergency medicine personnel), anesthesiologists are potentially well-placed to assume a substantial role in such situations.

Basic additional training encompasses crisis leadership education, managing limited resources (including drugs, personnel, and equipment), proficiency in operating and communication within a multiagency environment, understanding the intricacies and constraints of triage and prehospital systems, and understanding the subtle yet specific patterns of injuries unique to hybrid and terrorism attack methodologies.

To be able to respond to a hybrid threat efficiently, it is imperative that anesthesiologists play an early and integral role in the mitigation and response planning. The well-known all-hazards approach is an excellent starting point for planning, mitigation, and initial response, but it is paramount that the synergistic and compounding effects of hybrid warfare are also considered. Relevant scenarios and simulation exercises should be incorporated into the disaster medicine training for residents and specialists to enhance resilience and mitigate the confusion of serving as an anesthesiologist during a hybrid attack. Fundamentally, clinicians at all levels should have a basic knowledge of the different components of hybrid warfare, and how to prepare for them.