Retired officers and current commanders are warning that a deepening Russia-China military partnership could strip away a key U.S. edge beneath the waves, raising the stakes around Taiwan and the broader Indo-Pacific. Experts point to alleged transfers of submarine quieting know-how, reciprocal industrial support, and a transactional pattern of capability swaps that make planning and deterrence harder. The risk is clear: quieter adversary submarines would complicate detection, tracking, and the preservation of American freedom of action in contested waters.
Retired Rear Adm. Mark Montgomery has been blunt about what is unfolding and why it matters to American defense planners. “Russia is giving incredibly important technology to China. They’re allegedly giving them submarine quieting technology,” Montgomery said, warning that the balance under the sea could shift in ways Congress and the Pentagon need to treat as urgent. From a Republican perspective, this should trigger immediate reassessments of production, alliance support, and undersea investments.
Submarine quieting is not a buzzword; it is the single most important factor in making a sub hard to find and even harder to target. Modern navies spend decades and massive budgets reducing acoustic signatures because a silent submarine can control sea lanes, gather intelligence, and hold high-value targets at risk. Any outside help that accelerates those gains for a rival shortens the time the U.S. and its partners have to respond effectively.
The Navy’s advantage has long rested on stealth, sensors, and trained crews who exploit undersea superiority to deter conflict and win if deterrence fails. China has been modernizing quickly but historically lagged in propulsion and quieting; outside assistance from Moscow could erase that gap much faster. “Any weakening of our asymmetric advantage in undersea warfare is a big deal,” Montgomery cautioned, and policymakers should treat that warning like a red flag.
The Chinese Embassy did not directly address whether Beijing has received Russian submarine-quieting technology when asked, and instead reiterated a familiar line. “Military cooperation between China and Russia consistently adheres to the principles of non-alliance, non-confrontation, and non-targeting of third parties, playing a significant role in safeguarding the sovereignty and security of both nations and maintaining international and regional peace and stability,” the embassy said in a statement. “We hope that relevant parties will view China-Russia military cooperation objectively and rationally, and stop groundless speculation.”
Senior U.S. commanders have voiced the same worry in official settings, describing exchanges of niche but consequential technologies. Adm. Samuel Paparo told the Senate Armed Services Committee that China was receiving “potentially submarine quieting help” from Russia, a phrase that should set off procurement and intelligence alarms in Washington. Those are not idle remarks; they reflect what happens when two revisionist powers trade the tools they each lack.
The technological swap goes both ways: China has supplied Russia with machine tools and legacy electronic components that kept Russian production lines running under wartime pressure. Commanders testified that Beijing provided large shares of the hardware Moscow needed to repair and manufacture munitions, helping sustain a costly conflict. In return, Moscow appears willing to share advanced niche systems where it still holds expertise.
That back-and-forth has analysts describing the relationship as transactional by design, not accidental. “This transactional relationship is putting the United States and its most important allies and partners at risk,” Montgomery said, arguing that capability exchanges create hard-to-fight, cross-domain problems. When weapons, training, and industrial lifelines flow both ways, adversaries knit together complementary strengths that can overwhelm single-theater responses.
Specific examples of cooperation and transfer have emerged in reporting and investigations, from drone production to training and equipment sharing. A 2025 investigation found arrangements to produce attack drones with mixed components and contracts showing training and equipment transfers that expand China’s options and Russia’s resilience. Those patterns matter because they show intent to build mutual capacity, not just occasional barter.
For the U.S., the most immediate operational concern centers on Taiwan and the surrounding seas, where American submarines are central to deterrence and wartime plans. Quieter Chinese submarines would complicate tracking, reduce warning time, and make counterforce operations riskier for surface and undersea fleets alike. That operational friction is exactly what planners dread when calculating scenarios involving the island and the larger Indo-Pacific balance.
Montgomery ties these developments to the argument he lays out in “Axis of Aggressors,” framing the transfers as part of a broader strategic problem across Europe and Asia. The pattern is transactional, cumulative, and aimed at eroding the technical edges that have kept the United States and its partners ahead. Requests for comment to the Russian embassy went unanswered, and U.S. Indo-Pacific Command declined to comment on specifics when contacted.
