There has been a long-running chatter in the media and certain circles in Washington about President Joe Biden’s fitness for carrying out the duties of the presidency, especially when it comes to ordering the use of nuclear weapons. This discourse has overlapped with other events that also provoked discussion about civil-military relations, including the nuclear chain of command and potential risks to its viability. Defense Secretary Lloyd Austin was hospitalized in late December 2023 and early January 2024. He was criticized by some commentators and members of Congress for his failure to communicate in a timely manner with Department of Defense staff and the White House. 

Moreover, in mid-February 2024, Congressman Michael Turner (R-OH,) a member of the House Armed Services Committee, went public with alarms about a Russian anti-satellite weapon (ASAT) possibly configured to detonate a nuclear explosion in outer space, thus threatening the survivability of U.S. space-based reconnaissance, communication, navigation, and command-control assets.

Much of this concern about the U.S. chain of command for authorizing nuclear first use or retaliation was understandable yet, for the most part, based on misinformation or purely political motives. 

First, Joe Biden’s occasional gaffes have been exaggerated in their significance. Former President Ronald Reagan was subjected to similar political attacks and media criticism, especially during his second term. In addition, mental capacity cannot and should not be diagnosed from a distance or by persons untrained in medicine. 

As in the case of his predecessors in the White House, Biden is constantly monitored by physicians of the highest quality and regularly assessed for his mental and physical competency. The bubble of media coverage of every presidential move and the normal propensity for governments to leak even about confidential matters makes it unlikely that a nonfunctional president could be concealed from public view for very long. Gone are the days when President Woodrow Wilson’s spouse could run the White House for an extended period without public awareness or when “Dr. Feelgood” administered a variety of injections and pills to President John F. Kennedy to keep up his appearance of vim and vigor. Frankly, much of the criticism of Biden on this point is simply ageism.

Second, Austin has admitted that he could have done a better job communicating with his staff, the White House, and the media, but calls for his dismissal are disproportionate. Regardless of his temporary medical condition, the military chain of command’s stability was never in doubt. As commander-in-chief of the armed forces, the president is the first link in the chain, followed by the secretary of defense, and then to the unified and specified combatant commanders who actually operate the military forces (U.S. Strategic Command, Indo-Pacific Command, and so forth). Bureaucracy can be cumbersome and slow in some of its day-to-day operations. Still, it has the advantage that every position has an individual directly beneath it presumably available for replacement (recall Mel Gibson’s admonition to his troops in the movie We Were Soldiers: “Teach your job to the person below you and learn the job of the person above you”).

As harsh as it might sound, some military officers have a brutal way of driving this point home to their subordinates: “Cemeteries are full of people who were indispensable.” The U.S. president must approve the first or retaliatory use of nuclear weapons. If the president is incapacitated or otherwise incapable of making a decision, authority cascades down the chain of command to the secretary of defense and combatant commanders. It is important to note that the military chain of command is different from the political order of succession to the presidency, which runs from the vice president to the speaker of the House, to the president pro tem of the Senate, and then to cabinet secretaries, in the order of creation of their offices (Department of State, Department of Defense, etc.).

There are several safeguards and constraints built into the U.S. system concerning the possibility of presidential rogue behavior, including nuclear adventurism. First, the president can be removed from office via the procedures set forth in the 25th Amendment to the U.S. Constitution. The process is set in motion if the vice president and a majority of the cabinet declare that the president is unfit to continue serving in that capacity. Second, on the military side of the equation, the senior officers of the armed forces are sworn to uphold the Constitution of the United States against all enemies, foreign and domestic. 

A U.S. president, having taken leave of his or her senses and ordering a nuclear first use for no compelling reason, would find that slow rolling and passive resistance are works of art in the military chain of command and defense bureaucracy. Delays in relaying orders down the chain of command would intervene until the president had second thoughts or the Twenty-fifth Amendment kicked in. For example, during President Richard Nixon’s last days in office, there were concerns that he might misuse elements of the armed forces to protect his tenure in office. Accordingly, then Secretary of Defense James Schlesinger quietly issued instructions through appropriate channels that any presidential order moving forces currently deployed within the United States would first be routed through the Office of the Secretary of Defense for confirmation before troops were moved.

Another set of concerns about the U.S. nuclear chain of command’s stability and flexibility were raised by February 2024 reports of a Russian nuclear space bomb that was reportedly in an advanced stage of research and development and potential deployment. It was not clear whether officials were talking about a true nuclear detonation in space or a nuclear-powered satellite capable of using mechanical or other means to destroy other countries’ satellites. Detonation of a nuclear weapon in space would arguably not be in anyone’s interest. Although the vacuum of space would preclude major blast effects that would otherwise occur during an atmospheric explosion, significant heat and radiation could disable or destroy hundreds or thousands of satellites, including those belonging to Russia or its ally China. 

A more likely scenario is that a Russian RPO (rendezvous and proximity operations) satellite would maneuver its trajectory to within striking distance of an American satellite and disable it with directed energy or electronic weapons or, if necessary, by colliding with it at high speed. Regardless, the scenario raises serious issues for the United States’ ability to carry out space-based reconnaissance, command-control, communications, navigation, targeting, and other missions. A space-based Pearl Harbor could be the prelude to a terrestrial nuclear attack, especially if that attack was accompanied or preceded by cyberwar that contributed to additional confusion in the U.S. decisionmaking and response. Space and cyber have become the great enablers of a capability for global military operations in real-time, and therefore, attractive backdoors for planners of a nuclear first strike against the United States and/or its allies.

On the other hand, even if denied some of its space-based capabilities and/or attacked by cyber hackers in the prelude to a nuclear first strike, the United States would not be paralyzed from retaliation that would provide unacceptable destruction by historical standards against any attacker or attackers. Not all of the reasons for this assertion can be discussed in the public domain. Still, in general, U.S. defense planners have built into the system default plans and capabilities for worst-case scenarios, including a nuclear surprise attack on the American homeland and/or its allies and partners. 

It should also be recalled that two other nuclear weapons states are U.S. NATO allies. The United Kingdom has a strategic nuclear force of submarine-launched ballistic missiles (SLBMs). France has its own SLBM force plus airborne nuclear delivery systems, some located on land and some based on carriers. A nuclear attack on the United States or its nuclear-capable allies would invoke Article V of the NATO charter, presenting to prospective attackers the complexity of three enemy target bases, command and control systems, and deployed nuclear forces, some of which are not first-strike vulnerable. 

Understanding this situation is important because some military experts fear that China’s growing strategic nuclear forces combined with those of Russia could present a future nullification of U.S. deterrence credibility. This is a valid concern, but the full extent of China’s nuclear military buildup is still undetermined, and future arms control negotiations between the United States and Russia, if they ever resume, should also include China and limit the size and speed of any nuclear arms race. Meanwhile, the United States has not been standing still: the Biden strategic nuclear modernization program replaces all three legs of the U.S. strategic nuclear triad with new delivery systems and pushes forward with research and development for advanced missile defense systems against prospective threats.

However, going forward, two new concerns about the U.S. nuclear chain of command present themselves. The first is the growing development and deployment of hypersonic weapons, including nuclear ones, by major powers, including Russia, China, and the United States. Hypersonic glide vehicles or stealthy cruise missiles can combine advanced speed with evasion tactics against defenses, reducing the ability of defenders to detect launches, track attacking threat vehicles, and have the time necessary for a considered and deliberate response. In the case of the United States, time for consultation among the president and his or her advisors might be a matter of a few minutes or less, depending on the size and trajectory of the attack. 

Second, in response to the acceleration of prompt threats, some might suggest fully automating the nuclear warning, attack characterization, and response systems, perhaps with advanced artificial intelligence systems. Although future technology will doubtless permit automation of some aspects of warning, command and control, and responsive decision for nuclear attack, the U.S. president must maintain sole authority for nuclear first use, first strike, or retaliation. 

Ideally, the same standard should apply to space-based attacks on American spaceborne strategic assets and to cyber attacks on American vital infrastructure, although their speed and stealth will also create a temptation for built-in automatic responses. Additionally, the timing for activating missile defenses in response to a credible warning of an attack will also be influenced by available technology and human decisionmaking processes. In all cases, the rule must be to convey continued confidence in the ability of the United States to react to nuclear first use or first strike with appropriate and deliberate responses, sensitive to policy guidance and the requirements for deterrence and defense.

Lawrence J. Korb is a senior fellow at American Progress and an adjunct professor at Georgetown University. He was previously a senior fellow and director of national security studies at the Council on Foreign Relations.

Stephen J. Cimbala is a distinguished professor of political science at Penn State Brandywine and the author of numerous books and articles on international security studies, defense policy, nuclear weapons and arms control, intelligence, and other fields.

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