Attack submarines from the Chinesenavy are becoming increasingly active in the Indian Ocean Region (IOR) and could pose a “grave threat” to Indian interests there, a report by the Indian defense ministry said last week.

Using subsurface contact information reportedly shared by the U.S. military, the report, prepared by the Integrated Defence Staff, said that at least 22 contacts had been made in the IOR in the past year alone, with the latest incident occurring in February. As India is confident that only two navies in the region — the U.S. Navy and the Indian Navy — have the capabilities to engage in such activity, the Indian military concluded that the boats involved were very likely from the People’s Liberation Army Navy (PLAN).

Indian media said the report proved that a fleet of Chinese nuclear submarines was making “frequent forays into the Indian Ocean.”

According to the report, titled Indian Navy: Perceived Threats to Subsurface Deterrent Capability and Preparedness, the “implicit focus” of the PLAN appeared to be undermining the Indian Navy’s ability “to control highly sensitive sea lines of communication” within the region. For the time being, however, China’s intent more likely was to determine the Indian Navy’s ability to detect undersea objects. The report added that the PLAN’s “extended patrols may fully overlap with the Indian Navy’s area of operation.”

The focus of such deployments, the report said, was the IOR, a sea area that spans from waters off the Horn of Africa to the Malacca Strait and the western shores of Australia.

According to India Today’s coverage of the report, one contact with a suspected Chinese submarine took place 90 km from Indian soil in the Andaman and Nicobar Islands, while six took place northwest of the Straits of Malacca, 13 south of Sri Lanka and two in the Arabian Sea. The submarines were believed to be from the South Sea Fleet based at Sanya on Hainan Island, off China’s southern coast.

In May 2012, China announced that it could deploy Type 094 nuclear submarines at Yulin Naval Base at Sanya as part of its long-term strategy in the South China Sea. The SSBN will eventually be outfitted with outfitted with the JL-2 Sea Launched Ballistic Missiles (SLBMs).

The number of confirmed contacts mentioned in the report represented a marked increase from four year ago, when U.S. intelligence reportedly revealed that China’s fleet of more than 50 submarines had carried out 12 “extended patrols” outside its territorial waters in 2008, up from six the previous year. Reports then did not indicate where the extended patrols were said to have taken place, though it can be assumed that some occurred near or within the IOR.

Such signs of increasing activity in the IOR have fostered fears — and those were reflected in the report — that the PLAN may have embarked on a project to “strangulate” India.

Port facilities in Gwadar, Pakistan, close to the border with Iran, which China has is suspected of seeking to turn into a naval facility as part of its “string of pearls” in the region, would give the PLAN “enormous command and control capability for prospective … presence in the IOR,” the report warned.

Furthermore, the report said, the Chinese Navy appears to be building “expeditionary maritime capabilities” and could use nuclear-powered submarines and area denial weapons such as the DF-21D anti-ship ballistic missile to threaten India within the region.

Some Indian analysts, however, have gone on the record saying that such assessments tend to overstate thenature of the threat and the viability of the “strong of pearls” as a means to transform PLAN adventurism in the area into a more permanent presence. Still, the growing frequency of PLAN submarines in the IOR is yet another sign — and this shouldn’t be surprising to anyone anymore — that China has ambitions to become a global naval player. The waters are also becoming increasingly important for China, as its energy imports from Africa and the Middle East, which must transit the IOR, continue to grow.