As the world doomscrolls through the grim news from Ukraine, it’s time to reassess the risks created by sizing the U.S. military to fight a single major conflict.

The 2018 National Defense Strategy was a watershed document that shifted DOD’s focus toward defeating Chinese or Russian aggression, defending the U.S. homeland, sustaining nuclear deterrence, and deterring — but not defeating — a lesser aggressor in another theater.

The 2018 NDS also broke with DOD’s long-established requirement to size its forces for two theater conflicts. The risks associated with maintaining a one-war force are apparent as Russia continues to assault Ukraine and China expands its influence in the Pacific. It’s not too late for the Defense Department to address this in its forthcoming National Defense Strategy.

Chief among these risks is a one-war force invites opportunistic aggression in a second theater. As DOD informed Congress after the Cold War, a two-war military was critical to preventing “a potential aggressor in one region to be tempted to take advantage if we are already engaged in halting aggression in another.” This is an increasingly plausible scenario given Russia’s willingness to forcibly recreate a geographic buffer between itself and NATO, and the growing strategic relationship between China and Russia.

This does not mean China and Russia will soon form a pact to fight a war with the United States. Rather, China could decide to take advantage of a Russian campaign against NATO in Europe, or Russia could make a move after China launches an attack on Taiwan. It’s also plausible they could coordinate the timing of their actions.

In either case, a one-war U.S. military lacks the forces, munitions, logistics, and other capabilities needed to respond in both theaters. Force cuts in search of a “peace dividend” and the failure to modernize our military as it fought small wars in the Middle East have resulted in a force that is too small and too old. China and Russia know the U.S. Air Force now has about half the aircraft it had in 1991, and the Navy lacks enough ships, carrier aircraft, and undersea forces to meet its global commitments.

Critics of rebuilding a two-war force are concerned with its cost and its potential to dilute the resources DOD needs to modernize for a China fight. “China first” advocates are not completely wrong if our military services fail to ask for what they would need. Today, they accept what they are given — and less than they need — to develop their plans and programs. This is based on their anticipation of future budgets, not future threats.

This does not mean DOD’s budget should grow to unrealistic levels. Increasing defense spending beyond its current level of roughly 3% of GDP is not unreasonable, given it averaged about 6% of GDP during the Cold War. Even 1% of GDP growth would give DOD about $200 billion more a year, enough to buy a larger fleet, adequate next-generation combat aircraft, AI-enabled unmanned systems, advanced munitions and other capabilities to defeat a Chinese attack and deter Russia.

Selectively reallocating budget shares across the services would be another step toward rebuilding a two-war force. This reallocation should be based on the predominant forces needed for a conflict in the Indo-Pacific and another in Europe — not every service needs to chase the Chinese “pacing threat.” The fact is a conflict with China would take place mostly at sea and in the air, space, and cyberspace; it would not be a boots-on-the-ground land war. On the other hand, a fight to defend NATO’s eastern frontier would be dominated by land, air, space, and cyberspace.

In other words, a two-war force would be more affordable if DOD exerts some discipline and reduces investments in overly redundant and costly capabilities some services are developing for the Pacific. This includes long-range hypersonic weapons the Army desires that cost $40 million to $50 million each. DOD could better use these resources to acquire more air, space, and cyber forces that can respond within hours to strike invading forces in the Indo-Pacific and Europe.

This approach would be a major step toward creating a force that can credibly deter opportunistic aggression. The next NDS will maintain China as the Defense Department’s pacing challenge and unlikely to support rebuilding a two-war force. It’s time to acknowledge that a “China first” strategy is really a China only strategy that creates a path for Russia to win in Europe if the U.S. military is fully engaged in the Pacific.

Our European allies have heard the wake-up call and understand the need to bolster their defenses to counter Russia. DOD and the Congress must also acknowledge this reality. The choices they make should be informed by a strategy that reduces risk of opportunistic aggression in a second theater, not a spending level proposed by the administration. This should be the purpose of the 2022 National Defense Strategy.

Retired U.S. Air Force Col. Mark Gunzinger is director for future concepts and capability assessments at the Mitchell Institute. He previously served as deputy assistant secretary of defense for forces transformation and resources within the policy office of the Office of the Secretary of Defense. Kamilla Gunzinger is a senior program director at the Mitchell Institute.

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