In an interview with “60 Minutes” this month, President Joe Biden was asked about how many crises the United States can “take on” at once. Biden replied, essentially, that America can handle anything. But as the United States courts strategic overstretch with possible involvement in multiple foreign conflicts, concerns about its own military readiness are becoming harder to ignore.

Training exercises are not preparing units for the realities of the modern battlefield, sustainment issues are keeping complex platforms out of action, and a high operational tempo driven by “forward presence” missions is pushing the joint force to a breaking point. Pentagon leadership might be loath to acknowledge it, but the military has a growing readiness problem on its hands.

Take ground forces. The war in Ukraine illustrates how the lethality of the modern battlefield punishes militaries unable to integrate cover, concealment, dispersion, suppression, small unit independent maneuver, and combined arms into their tactics. The Army, however, is still advocating doctrinal concepts favoring centralized theater-level decision-making and large unit maneuver, as opposed to enabling warfighters at the brigade level to act independently to rapidly seize the initiative. Some analysts are already highlighting the risks of this approach. A paper published by the U.S. Army War College in August observed that maturing technologies like unmanned systems will “dramatically accelerate the pace of modern war” and Army leaders “cannot expect a brigade that micromanages garrison tasks to execute combat operations successfully.”

The Army’s Combat Training Center exercises that brigades participate in every 18 months also fall short of replicating the battlefield conditions the United States would confront against near-peer adversaries. As Army Maj. Robert G. Rose recently explained, opposing forces in CTC exercises do not construct a defense in depth, utilize reserves for counter-attacks, employ mass artillery, or build dense minefields to thwart Army units trying to improve their maneuver warfare techniques. Yet in Ukraine, Russian forces have successfully employed all of these elements to frustrate Kyiv’s counteroffensive.

While U.S. ground forces aren’t training for the right fight, critical air power assets might not be ready to fight at all. Since its inception two decades ago, the F-35 Joint Strike Fighter program has become known more for its performance mishaps than as the world’s premier fifth-generation fighter. Just last month, a Marine Corps pilot was likely automatically ejected by his F-35 over a populated area in South Carolina before the $100 million aircraft crashed. The Marine Corps hasn’t commented on why the ejection occurred, though faulty sensors and perhaps even mild turbulence may be to blame.

But a broader issue is keeping hundreds of F-35s grounded: sustainment. According to a report from the Government Accountability Office last month, military maintainers are facing several challenges keeping the F-35 fleet in the air, including insufficient and unavailable technical data, spare parts, and support equipment. Since Lockheed Martin has proprietary ownership of F-35 technical data, uniformed maintainers must wait for the company to send a representative to assess and remedy problems with the aircraft — a process that can take more than four months to complete.

The consequences for readiness are predictable: Less than 60% of the F-35 fleet is mission capable. Operational Marine Corps F-35Bs and Navy F-35Cs have abysmal mission-capable rates of 25% and 30%, respectively. This is to say nothing of the aerial tankers responsible for refueling F-35s midflight — a critical logistical requirement in the Pacific. According to the latest GAO figures, the Marine Corps and Navy’s aerial refueling tankers didn’t meet their annual mission capable goals once from 2011-2021. The Air Force’s KC-10 and KC-135 tankers only met their goals for one and three years, respectively, during that same period.

For all of the F-35’s woes, nothing compares to the readiness crisis facing the Navy. The main source of the Navy’s problems is that its operational tempo is too high, running aging ships and their undermanned crews ragged. The consequences can be disastrous. In 2020, a devastating fire on the USS Bonhomme Richard forced the Navy to scrap the $1.2 billion warship. An investigation later found that training, maintenance and command failures allowed the fire to burn unnoticed for hours before it engulfed the ship. Just this year, six Navy commanders have been relieved of duty due to “loss of confidence.” In September, the USS Ronald Reagan was forced to delay its departure from Japan seven times, with one report claiming the Nimitz-class aircraft carrier’s repeated delay was due to a pipe rupture that left the ship without any fresh water supply.

The Navy’s shipyards aren’t in good shape either. Aging equipment and facilities, increasing material costs, schedule overruns, and high workforce turnover are handicapping the Navy’s ability to maintain its ships and submarines, leading to thousands of “delay days.” Along with maintenance backlogs, the Navy also isn’t building enough new ships to deter America’s adversaries. A recent Office of Naval Intelligence report noted that China’s shipbuilding capacity is now more than 200 times more capable than that of the United States.

These issues aren’t just confined to the surface fleet. The Pentagon is demanding delivery of at least two Virginia-class attack submarines a year, but capacity problems mean only 1.2 are built annually.

There are no easy solutions for the military’s mounting readiness issues, but the first step is to acknowledge that they exist. The core of America’s military remains strong. But if Pentagon leaders don’t address the military’s readiness problems soon, they might be in for a rude awakening about how much the joint force can handle.

Michael P. DiMino is a fellow at Defense Priorities, and a former career intelligence officer. His views are his own and do not represent those of the United States government. Matthew C. Mai is a research associate at Defense Priorities.