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In 1869, Charles Minard, a French engineer, created a famous illustration, now known as the . It depicts Napoleon’s invasion of Russia with a thick gold band representing his initial army of over 400,000 men and a thin black line illustrating his drastically reduced force of about 10,000 returning. Beyond the staggering losses, the chart shows other things too: geography, the passage of time, temperature fluctuations. What it does not show, but implies, is Russia’s advantage in strategic depth. Strategic depth allowed Moscow to draw in Napoleon's forces. The Imperial Army then stood by as Napoleon’s forces , denying them the opportunity for a decisive battle. Russia’s vast land and resources gave it the ability to apply sustained pressure on the French army, eventually driving it out. Strategic depth gave Russia time and room to maneuver.

Strategic depth has always been a critical factor in war. Historically, the term mostly applied to geography. It captured the idea that the further your enemy had to physically travel to get to your government center or vital resources—what Clausewitz often referred to as a country’s “center of gravity”—the more time and space you had to adapt, recover, and counterattack. For the United States, its oceans provided strategic depth; Russia and China relied on their vast landmasses.

Technology, however, has devalued the traditional advantages conferred by strategic depth. This month a squadron of Ukrainian drones managed to achieve what Napoleon could not: deliver a against a military target deep within Russian territory, and thereby disrupt one of the tenets of classical warfare.

Moreover, we can no longer measure strategic depth by miles alone. Digital networks, satellites, global supply chains, and geopolitical influence allow adversaries to degrade our defenses and to strengthen their ability to maneuver in ways that bypass traditional borders altogether. Strategic depth, either naturally occurring or proactively shaped, affords a government and citizens more time to make decisions, and more operational flexibility to organize responses, protect power centers, and take steps to ensure national survival in the event of external aggression. If the United States wants to maintain its military edge and deter future wars, it should consider how to expand and apply the concept of strategic depth. It might start with three principles.

First, we need to think beyond terrain. Strategic depth now applies to cyberspace, outer space, and our defense industrial base.

In the cyber domain, the United States already has an excellent roadmap. proposed a strategy of "layered cyber deterrence�� to deny adversaries entry into U.S. systems, use diplomacy to push back on bad actors, and impose costs on those that cross the line. The Trump administration should continue to .

Outer space is another domain in which strategic depth is critical. The United States can no longer rely on a handful of powerful and expensive . We need swarms of cheaper satellites that can be deployed quickly, are harder to kill, and can be updated in real time. Deployments must be layered and spread across different orbits, while communications must be instant.

President Trump’s proposed will use space-based assets to improve strategic depth for the United States. Once deployed, the Golden Dome would establish across the entire American homeland a multi-layered defensive shield that is capable of such as ballistic missiles and hypersonics. Its multitude of sensors would allow the U.S. military to hostile missile attacks against the United States and then destroy the incoming projectile(s) with interceptors.

Then there’s our , which remains sluggish, expensive, and inflexible. It can still take a decade or more to field new weapons. A DIB that exhibits strategic depth requires the ability to adapt weapons systems quickly since adversaries will deploy countermeasures. Ukraine has shown how battlefield conditions force innovation on the fly—the Ukrainian military adjusted to counter Russian jamming, for instance. We must be able to do the same. And we can, if the United States harnesses its commercial strengths, prioritizes commercial solutions, and taps into commercial supply chains. A DIB that offers strategic depth means that defense leaders need to prioritize production at scale over bespoke systems. “Good enough and ready�� beats “perfect and late. To this end, the ability to produce at scale should be a consideration in weapon designs from the start.

Building a deep DIB also means avoiding single sources of supply, which are fragile and minimize the number of options that the United States has when procuring resources, inputs, and products. Such chokepoints are easy targets for adversaries. Achieving strategic depth will require the United States to eliminate dependencies on a single country or company for materials that affect our national and economic security. Instead, we should work to diversify our suppliers and reduce our reliance on China.

Ukraine’s cargo container on Russia’s strategic bomber fleet shows how modern technology overcomes strategic distance in the traditional sense. Russia is the champion of strategic distance and Ukraine neutralized it with a few cargo containers and drones. Strategic depth in this case requires a level of capability of and counterintelligence services that preclude this kind of operation.

A second principle of modern strategic depth is to defend forward through allies and partners. Recognizing that allies are our competitive advantage, we should back them when they respond to the aggression of common enemies. As the scholar Jakub Grygiel , “Washington should unleash our allies that want to defend themselves.��

Frontline states—such as Ukraine, Taiwan, and Israel—should be supported to divert the resources of adversaries. That gives us breathing room and operational flexibility. With U.S. backing, Israel has already severely degraded military capabilities and destroyed and . Similarly, with U.S. backing, Ukraine has the Russian military. Japan’s defense modernization and acquisitions—from stealth fighters to Tomahawks—are already China’s regional playbook.

American troops can also act as force and flexibility multipliers when deployed in key theaters alongside allied forces. When the United States positions military assets closer to regions of potential conflict, it adds additional layers of temporal distance between adversaries and the U.S. homeland. That’s classic strategic depth, updated for today.

China takes forward deployment seriously and uses it in different ways to gain strategic depth—including ways that do not involve uniformed troops. is China’s years-long effort to gain a foothold in communications, energy, transportation, water, and sewage systems throughout the United States. The former FBI director recognized this threat last year, that hackers were positioned “to cause real-world harm to American citizens and communities if or when China decides the time has come to strike.�� Should conflict break out—over Taiwan, for instance—it’s easy to imagine how China’s strategic depth inside the United States could wreak havoc and complicate Washington’s efforts on behalf of Taiwan.

China also has varying degrees of control over around across the globe. That includes like the Strait of Hormuz, the Red Sea, and even the Gulf of America. Through these ports, China can project force and influence far beyond its territory, in ways that could harm the United States before and during a conflict. Beijing has basically set up toll booths on the world’s shipping lanes. As Senator Todd Young put it, countries now have to ask Beijing “�� just to move goods. That’s strategic depth—and China is using it.

In addition, China is developing , which would allow it to deploy forward missiles using COSCO and its shipping empire. Imagine hundreds of prepositioned missiles taking out our fleet in port on Day One of a war, using container ships as the launchers.

Third, preoccupy our opponents by creating challenges. Think of it as “distraction by design.�� The Trump administration’s first on Iran did just that, forcing Tehran to tighten its belt, cut fewer checks to terrorist proxies, and respond to unrest at home. U.S. policies created inconvenient hurdles for Tehran. Today, on China also create complications for the CCP. When Beijing has to , find , or with Washington, that’s time and energy not spent on expanding influence. If we continue—especially by deepening ties with other partners like India or Vietnam—we can reduce the CCP’s ability to fund its and force it to focus on . With the resulting time, Washington and its partners can advance their own economic, diplomatic, and military initiatives to counter Beijing’s current advantages.

Today, strategic depth is about far more than land. It’s about flexibility: having additional options and time in an unpredictable geopolitical environment. Moreover, when adversaries have already reached inside U.S. systems, Washington has to think both defensively and offensively. Yes, strategic depth is about resilience, but it’s also about shaping the global environment in ways that give the United States time and space to act—and deny that same advantage to others. It’s about shaping the fight before it starts, proactively tilting the board in your favor—geopolitically, militarily, and economically.

The concept is old. The application must be new.