The twenty-first century will challenge the concept of deterrence in new ways. Some are already apparent. There are at least nine important components of the new metaverse for deterrence (or meta-deterrence) that will be significant for military planners, policymakers, and theorists.

The first component of the new metaverse for deterrence is the growing threat to states’ cybersecurity and the possibility of cyberwar. Cyberwar among state and non-state actors is already a significant challenge to international security. Cyberattacks occur as solo excursions or as supplements to the kinetic use of force. Both the public and private sectors are vulnerable to cyberwar, and the possibility of a crippling attack against American infrastructure, including military forces and command systems, requires constant vigilance and upgrades to information systems. In the case of nuclear deterrence, a nuclear first strike would probably be preceded by cyberattacks against the opponent’s early warning, command-and-control, and response systems in order to introduce confusion or paralysis that could delay or forestall an effective response.

Second, military uses of space and the ability to deny space superiority to potential U.S. adversaries will become primary concerns for the Defense Department. Partnerships between the U.S. government and high-end defense contractors are already exploring ways to increase the reliability and resilience of space-based and space-dependent systems for reconnaissance and surveillance, communications, early warning, command-and-control, and other functions. Both Russia and China have tested satellites for rendezvous and proximity operations (RPO) in various orbits, ostensibly for the inspection and repair of friendly satellites, but also capable of close inspection or destruction of adversaries’ systems if so tasked. U.S. options for increasing the resilience of orbital platforms include the proliferation of numerous smaller satellites in critical orbits, equipping satellites with defensive measures (including stealth and maneuverability), and developing offensive capabilities for responding to perceived threats. Legal issues arise with respect to whether an attack on critical mission satellites for national defense is tantamount to an attack on the American homeland or other vital military assets.

The third component of the new metaverse for deterrence is artificial intelligence (AI). Some even compare the advent of AI to the discovery of electricity and see it as an enabler of new possibilities in cognitive warfare, among other forms of warfare. Machines can already create encyclopedias, write novels, and mimic or surpass human capabilities in a variety of contexts. The smarter machines of the future will provide optimal pictures of the battlespace in real time, sensor-to-shooter links, and immediate post-attack assessments of damage inflicted and targets destroyed. On the other hand, the challenge of managing the human-machine “interface” will be considerable. Smart machines may drive decision-making toward pre-planned options and pre-established expectations about outcomes despite changes in exigent circumstances “on the ground.” Ethical and legal issues will also arise concerning how much control can be delegated to machines as opposed to the “human in the loop” when military strikes involve the possibility of collateral damage.

Fourth, the development of hypersonic weapons, including delivery systems for nuclear warheads, should raise serious issues for deterrence and defense planners. A reliable second-strike capability—making threats of retaliatory punishment credible—is a necessary condition for successful nuclear deterrence. Hypersonics compress the time available for warning and selecting an appropriate response to an attack. It is conceivable that national leaders might have only a few minutes from the initial launch detection of an enemy first strike to the arrival of warheads at their assigned targets. Under these conditions, leaders fearful of losing their deterrent might be more willing to authorize preemptive attacks instead of waiting for indisputable confirmation that a nuclear war is actually underway. An arms race in deploying hypersonic weapons could also affect conventional deterrence, as intermediate- and medium-range missiles with hypersonic speeds and maneuverability could inflict massive damage over a wide area within minutes instead of hours or days.

A fifth component of the new metaverse for deterrence is the growing capability of anti-missile and air defenses. With respect to ballistic missiles, the Cold War era was marked by a one-sided dominance of offensive systems over defenses. Improved technologies in missile defense against missiles of short, medium, and intermediate ranges have already been demonstrated by the United States and other countries. Future missile defenses based on new technologies or platforms, including space-based systems, might provide additional leverage against ballistic missile attacks. A race between states’ ability to field hypersonic offensive weapons compared to their capabilities for improving missile defenses is possible. In the realm of nuclear deterrence, missile defenses will always be challenged by the fact that even small numbers of nuclear weapons can do historically unprecedented damage. Therefore, amid the possibility of large-scale nuclear attacks against the homelands of major powers, deterrence by denial will remain less dependable than deterrence by credible threats of retaliatory punishment. On the other hand, defenses that are “good enough” to make the calculations of prospective first strikers more complicated might appeal to some national leaders and defense planners.

Sixth, Russia’s war against Ukraine has only underscored the growing significance of drones for future discussions of deterrence. Ukraine’s ability to strike at Russian military targets hundreds of kilometers inside Russian territory with relatively primitive drones was a game changer. As drones become more sophisticated and smarter, their appeal to major powers for deterrence and defense will only increase. Drone “swarms” might be used for large-scale attacks against military facilities or civilian infrastructure. On the other hand, drone swarms might also be used for anti-missile or air defenses. Swarms of hundreds, thousands, or even a million drones are no longer the stuff of fantasy. Apart from their potential for massive attacks, drones might also be employed for precision attacks against strategic targets such as bases, command centers, or even individual military or civilian leaders. Drones have also changed the game with respect to awareness of the battlespace. Inexpensive drones can now map an enemy’s movements of its ground and maritime forces in real time and share that information with commanders who can authorize prompt and effective responses.

The seventh component of this new metaverse is the growing possibility of conventional war waged within a nuclear context. As more states acquire nuclear weapons and improve their fourth-generation capabilities for conventional warfare, there is a growing danger that both nuclear and conventional military options will be treated as points on a single continuum instead of discrete packages of choices. Instead of planning for “nuclear” deterrence versus “conventional” war-fighting, theater commanders will likely develop packages of options with both nuclear and conventional weapons. In theory, this packaging might increase deterrence by making it more difficult for adversaries to correctly guess how the United States or other powers might respond to an attack. On the other hand, packaging nuclear and conventional responses within the same frame of reference for operational planning could undermine the nuclear “taboo” that has held since the bombing of Nagasaki. It might also increase the recklessness of leaders like Russian president Vladimir Putin who are willing to repeatedly brandish threats of nuclear first use amid an ongoing conventional war.

The eighth component is the apparent determination of China to join the United States and Russia as a nuclear superpower. A Defense Department report noted that China “will likely field a stockpile of about 1,500 warheads by its 2035 timeline” and is improving its military capabilities for conventional warfare as well as for nuclear deterrence across the board. China’s emergence as a nuclear superpower will change the playing field for nuclear arms control. On one hand, if Russia and the United States resume negotiations on strategic arms limitation despite their disagreements over the Ukraine war, it seems important for them to invite China to have a seat at the table. On the other hand, Washington and Moscow have years of experience in negotiating strategic nuclear arms control agreements that require a great deal of transparency about forces and their capabilities, including extensive monitoring and verification. It is doubtful that China would find this degree of intrusive oversight by the United States and Russia acceptable under present conditions. If China builds its long-range nuclear forces to U.S. and Russian levels, it might be willing to enter arms control negotiations with more confidence as a third party among equals. But there remains the challenge not only of sizing up the Chinese nuclear arsenal but of understanding Chinese military thinking about deterrence, especially nuclear deterrence.

Ninth, challenges to deterrence do not only arise outside the borders of states. Modern democracies, including the United States and its European allies, also face issues in their domestic politics and societies that bear at least indirectly on their ability to sustain military power in support of deterrence. Political extremism and polarization prevent the successful operation of consensus-building politics, which is vital to the health of democracy. In the United States, a former president called into question the very validity of the Constitution itself. In Germany, authorities recently uncovered and disrupted a far-right movement plotting to assassinate the chancellor and overthrow the government. A democracy besotted with nonbelievers in democratic constitutionalism, especially among its elites, will have difficulty engaging its citizens to make the necessary sacrifices for deterrence and national security. As Gen. Colin Powell noted, no foreign power can defeat the United States of America—only Americans can.