New Delhi is in the final stages of deciding one of the largest defense contracts in its history: a $9 to $10 billion deal to build six advanced submarines equipped with air-independent propulsion (AIP) technology, a decision that will shape the balance of power in the Indian Ocean for decades. But the competition between Germany's Thyssenkrupp Marine Systems and a Spanish rival has been complicated by an uncomfortable wrinkle: scrutiny over both bidders' past defense relationships with Pakistan, India's principal regional rival.

The stakes extend far beyond steel and hardware. Submarines represent one of the most consequential tools of naval deterrence, capable of operating silently for extended periods and striking without warning. AIP technology, which allows diesel-electric submarines to remain submerged for weeks rather than days, has become the benchmark for modern conventional submarines. Whichever company wins this contract will help determine the underwater capabilities of the Indian Navy through the middle of the century, at a moment when China's naval expansion in the Indian Ocean region has sharpened New Delhi's sense of urgency.

A Contract Freighted with History

India's relationship with submarine procurement has long been tangled with geopolitics. During the Cold War, India built much of its undersea fleet around Soviet and later Russian designs, while Pakistan cultivated its own submarine partnerships with Western and Chinese suppliers. That history means Indian defense planners view any vendor's prior dealings with Islamabad through a lens of suspicion, regardless of how commercially routine those dealings may have been.

Germany's shipbuilding industry has a long history of exporting submarine technology worldwide, including to Pakistan's navy in past decades. Spain's shipbuilding sector has similarly cultivated defense export relationships across South Asia and the Middle East. For Indian officials evaluating the current bids, the challenge is determining whether either company's Pakistan-linked partnerships pose a genuine security risk, such as the potential for sensitive design information to leak to Pakistani engineers, or whether the concern is more symbolic than substantive.

Indian naval planners have historically treated any vendor's Pakistan connections as a red flag, even when the underlying commercial relationship long predates the current contract.

This is not merely bureaucratic caution. India and Pakistan have fought four wars and remain locked in one of the world's most militarized rivalries, centered on the disputed region of Kashmir but extending into naval competition across the Arabian Sea. Any perception that a foreign contractor might be simultaneously arming both Delhi and Islamabad, even indirectly through subsidiaries or historical contracts, invites intense parliamentary and media scrutiny in India.

Strategic Timing

The submarine decision arrives as India's navy confronts a shrinking undersea fleet even as regional threats multiply. China has steadily expanded its naval footprint in the Indian Ocean, developing port access and logistics arrangements in countries surrounding India, a strategy that Indian strategists have long viewed as an attempt at encirclement. Modernizing the submarine fleet with AIP-capable vessels is widely seen within India's defense establishment as essential to maintaining a credible deterrent and preserving freedom of navigation in waters critical to global trade.

The choice between the German and Spanish bids also carries implications for India's broader push toward domestic defense manufacturing. Under the government's "Make in India" initiative, foreign vendors competing for major defense contracts are typically required to partner with Indian shipyards and transfer significant technology, an arrangement intended to build indigenous capability over time. Both bidders in this competition will need to demonstrate not just technical superiority but a credible plan for technology transfer and local production, in addition to satisfying security concerns about their historical client lists.

What Comes Next

Indian defense officials have not publicly detailed the specific nature of either company's Pakistan-related ties, nor indicated how heavily that history will weigh in the final decision. Cost, technical specifications, delivery timelines, and the terms of technology transfer are likely to remain the dominant factors. But the fact that Pakistan's shadow looms over a contract meant to strengthen India's navy against a rising China illustrates how thoroughly the India-Pakistan rivalry continues to shape decisions far beyond the two countries' shared border.

A final decision is expected to be closely watched not only in Berlin and Madrid, but in Islamabad and Beijing as well, given the contract's implications for the underwater military balance across South Asia.