Simultaneity: You Only Need a Two-Body Problem to Be Screwed

The 2026 National Defense Strategy (NDS) made an admission that its predecessors only implied: the United States cannot realistically plan to fight two major wars simultaneously and should instead focus on building a military capable of deterring China. By explicitly subordinating all other major warfighting missions to the Indo-Pacific, the strategy accepted risk in Europe and the Middle East as deliberate planning assumptions. Those assumptions are now being stress-tested in real time.

Today, the United States faces active combat operations against Iran, Russia’s ongoing illegal war in Europe, and accelerating pressure from the People’s Liberation Army on Taiwan. Three concurrent contingencies, not one sequential challenge.

The simultaneity question is no longer theoretical. The question is whether the force structure, munitions inventory, industrial base, and allied burden-sharing assumptions that underpin American deterrence are adequate, and what adjustments are required before the next contingency arrives on a schedule of the adversary’s choosing.

Force Structure

The simultaneity problem falls hardest on the U.S. Air Force and Navy because these are the services through which the United States projects decisive military power across theater boundaries. They are also most acutely constrained by capacity limits that no decision can resolve quickly.¹ Their equipment is costly and takes years or even decades to develop, build, and field.

The Navy currently fields 293 battle force ships against a goal of 381 manned ships plus 134 large, unmanned surface and underwater vehicles, a shortfall of nearly 90 hulls.² Shipyard industrial constraints have reduced production rates for Virginia-class submarines and DDG-51 destroyers, both critical to any Indo-Pacific campaign. The Iran War has committed three carrier strike groups to CENTCOM, essentially all the deployable carrier aviation capacity at a moment when INDOPACOM planners assess that deterring a Taiwan Strait contingency requires persistent carrier presence across the Pacific. A RAND Corporation analysis of Navy force structure concluded that force employment and development shortfalls are likely the result of poor force design decisions made decades ago, a structural deficit that no near-term procurement decision can fully correct.³

The Air Force faces an analogous constraint expressed differently. Air Force Materiel Command acknowledged publicly that the service relies on outdated logistics practices that create shortfalls in strategically pre-positioned capabilities, limiting the operational flexibility required for agile combat employment in contested environments. Fighter inventory is declining—the F-15C/D retirement is not yet fully offset by F-35A deliveries—and the bomber fleet, despite the B-21 program, will remain small relative to two-theater strike requirements for years. Distributed basing concepts designed for Indo-Pacific survivability may prove incompatible with the sortie generation rates that simultaneous Middle East and Pacific commitments demand.⁴

The Army, while not the primary instrument of Indo-Pacific power projection, carries simultaneity burdens that deserve acknowledgment. Recent transformation decisions—such as converting Infantry Brigade Combat Teams (BCTs) to more mobile configurations and reducing rotational presence in Europe—are working to optimize the land force for a China-first strategy while reducing its mass and weight relevant to a NATO contingency. If a European crisis materialized while Army divisions are committed to the Pacific in either a China or North Korea scenario, the United States would have limited ground combat power available to reinforce NATO allies on the timeline that Russian operational tempo would demand.

Multi-Theater Demands

The simultaneity challenge looks different across multi-theater pairings, and that differentiation matters for force design in ways that aggregate planning often obscures.

A China-Russia simultaneous scenario would place maximum pressure on naval and air forces in opposite hemispheres. Pacific naval assets committed to a Taiwan Strait campaign would be unavailable for blunting Russian submarine operations in the North Atlantic or sea control operations in the Baltic. Air Force long-range and fighter strike assets positioned and configured for Indo-Pacific operations are largely irrelevant to a European air campaign and repositioning them consumes days.

A China-Iran simultaneous scenario places concurrent demands on Navy aircraft carriers and destroyers, Air Force fighter and bomber squadrons, Army air defenders, precision munition inventories, and command-and-control systems all on a single joint force. The acting Navy secretary’s confirmation that Taiwan arms deliveries have been delayed because the American military needs those munitions in Iran is the most direct evidence of the problem. The same Tomahawk, Standard Missile-6, and JASSM-ER inventories that deter China are being expended against Iran, and production rates will struggle to restore them before a Taiwan contingency might materialize. The House Select Committee on the Chinese Communist Party found that the United States and Taiwan ran low on critical munitions within days of a Taiwan Strait conflict, a finding rendered more alarming by the reality of ongoing, unexpected wartime consumption in another theater.⁵

A China-North Korea simultaneous scenario may appear redundant, but the combined demand for theater missile defense interceptors, ground forces, and air superiority assets would strain even a force exclusively committed to the Pacific. The geographic overlap does not reduce the simultaneity burden; it concentrates it in ways that could overwhelm theater-level planning.

Allied Burden-Shifting: The Right Destination, the Wrong Timeline

The 2026 NDS proposes to resolve the simultaneity problem primarily through allied burden-shifting; Europe handles Russia, Japan and South Korea backstop the United States in the broader Pacific, and regional partners manage residual Middle East requirements. As a long-term objective this is sound. As a near-term operational assumption, it is dangerously premature. It relies on underdeveloped allied military capacity to bear the burden being transferred to it.

Canceling the 2nd Armored BCT rotation to Poland and removing the long-range fires battalion from Europe may be defensible as strategic endpoints—but as near-term transition steps, they are happening faster than European military development can absorb. European NATO members have increased defense spending, with the Eastern European countries exceeding 3.5 percent or even 4.5 percent of GDP on defense, but as a whole Europe is only just beginning to pass 2 percent. Increased defense spending translates into delivered military capability only after equipment procurement, training, and operational integration cycles that run five to 10 years. Reducing American forward presence before European forces are ready to substitute is not burden-sharing; it is burden-transferring to a recipient that cannot yet carry the load. The risk is a window of reduced deterrence that Russian planners may exploit because it appears temporary.

In the Indo-Pacific, Japan, Australia, and South Korea are all moving in the right direction—but none can substitute for high-end American capability, and planning assumptions that treat aspirational allied capacity as operational reality introduce risk that combat experience consistently punishes.

Practical Adjustments: Procurement, Pre-Positioning, and Forward Posture

Three capability families deserve priority above all others: long-range precision munitions producible at sustained rates and lower costs sufficient to support active combat in one theater while maintaining deterrent inventories in another; theater air and missile defense interceptors across all tiers from low-cost counter drones and cruise missiles to Patriot PAC-3s to the next-generation interceptor; and undersea warfare assets, both manned and unmanned systems.

The emphasis should shift from exquisite unit capability toward enough capable systems produced at scale. A smaller inventory of perfect weapons is strategically inferior to a larger inventory of adequate weapons when the binding constraint is simultaneity rather than single-theater sophistication. The FY2026 National Defense Authorization Act’s authorization of more than $25 billion for munitions points in the right direction; execution must match the legislative intent.⁶ The FY2027 administration proposal for $70 billion in munitions is even more ambitious.⁷

Pre-positioned war reserve stocks, sufficient to sustain the opening weeks of a second-theater contingency, are equally critical. Munitions stocks pre-positioned in the Pacific reduce logistics burdens when a conflict is most likely to be decided. Air and missile defense interceptors pre-positioned in Eastern Europe similarly reduce the time-to-effectiveness gap if a NATO contingency erupts while forces are committed elsewhere.

In forward posture, further reductions from Europe should be conditioned on demonstrated allied capability milestones rather than budget or political timelines. The presence of U.S. forces in Europe is not merely a military capability; it is a deterrent signal that has shaped Russian strategic calculations for eight decades.

The Deterrence Imperative

Deterring simultaneous contingencies does not require the ability to fight and win two major wars at once. It requires convincing adversaries that initiating a second contingency while one is ongoing will be prohibitive and painful rather than opportunistic. That conviction rests on visible military capacity, credible allied contribution, and pre-positioned capability that reduces vulnerability that simultaneous crises would otherwise open. The adversary coalition—Russia, China, Iran, and North Korea—has demonstrated the will and capacity to coordinate pressure across theaters. American deterrence strategy must be designed to deny the opportunities that coordination is designed to exploit. The United States currently falls short across force structure, munitions depth, and allied readiness. Closing those gaps is the defining defense management challenge of the decade ahead.