NOTAMs, Spy Ships and Strategic Signalling: India–China Cat-and-Mouse in the Bay of Bengal

Just one day before the scheduled test window, India cancelled the NOTAM. A second, much smaller corridor—suggesting a shorter-range missile—was issued for December 11, and then withdrawn again. In parallel, India issued a separate notification for a large Indian Air Force exercise in the Arabian Sea, unusually close—around 200 nautical miles—to Karachi, keeping Pakistan tactically engaged while developments unfolded in the Bay of Bengal.

The pattern repeated again in mid-December. A fresh NOTAM for December 17–20 initially marked a 2,250-kmcorridor, later expanded to 3,550 km. China responded by deploying a fifth research vessel, Da Yang Yi Hao, capable of deep-sea mineral and seabed research—assets considered valuable for modelling submarine operations. India cancelled this alert as well, and subsequently issued yet another NOTAM for December 22–24, with a corridor stretching roughly 3,240 km. Whether this final window will culminate in an actual missile test remains uncertain.

Defence analysts quoted by India Today suggest that the unusual frequency and last-minute reversals—rare in India’s test protocol—point to a low-cost counter-intelligence tactic rather than indecision. By varying corridor sizes and timings, India may be observing response times, positioning behaviour, and coordination patterns of Chinese vessels that routinely move into the IOR when Indian tests are anticipated. Such information, analysts argue, is critical for protecting future sea-based deterrent tests and denying adversaries clean data on missile flight profiles.

China’s interest is not incidental. Beijing has steadily expanded its IOR footprint, with access to ports at Djibouti, Gwadar (Pakistan) and Hambantota (Sri Lanka). Monitoring Indian missile tests—particularly submarine-launched systems—would help China refine anti-submarine warfare models and improve the survivability of its own next-generation platforms. The Bay of Bengal episodes echo earlier precedents: in November 2022, a Chinese tracking ship entered the Indian Ocean after India issued a missile-test NOTAM—only for India to cancel the test at the eleventh hour.

Why this matters:

The episode highlights how strategic competition increasingly plays out below the threshold of overt confrontation, using notices, logistics, and intelligence signalling rather than missiles themselves. For India, repeatedly shaping—and then denying—test windows may blunt adversarial surveillance and harden the credibility of its sea-based nuclear deterrent. For China, the deployments underline the premium it places on gathering undersea and telemetry data in India’s maritime backyard. The unfolding pattern suggests that the Bay of Bengal is becoming a contested intelligence theatre, where restraint and deception are as consequential as hardware.