New Delhi, Jan. 11: India has offered to train Bangladesh navy crews in operating submarines after Dhaka recently acquired the first of two boats from Beijing.

India has also agreed to host Vietnamese air force pilots to train in advanced combat techniques on Sukhoi fighter jets. Both the Indian and Vietnamese air forces fly variants of the Sukhoi 30 combat jets.

But it is New Delhi's offer to host Bangladesh submarine crews at INS Satavahana, the Indian Navy submarine academy at Visakhapatnam that is a delicate matter.

Bangladesh's recent acquisition of a Chinese Ming-class Type 035B submarine was initially a surprise for countries in the Bay of Bengal region. Despite China being a reasonably consistent supplier of equipment to the Bangladesh military, Dhaka's acquisition of the first of two-Ming-class submarines was surprising for most countries around the Bay of Bengal region. This is the first time the Bangladesh Navy has acquired undersea combat capability.

The Ming-class submarines supplied to China were built in the 1990s and were refurbished before being given to Bangladesh under a three-year-old contract. China is also understood to have trained a small Bangladeshi crew, as part of the contract, at its submarine base in Hainan Island at the rim of the South China Sea.

The Chinese People's Liberation Army Navy (PLAN) has over the years expanded its submarine fleet to more than 60, many of them the Type 093B nuclear-boats. This expansion has been accompanied by an increasing deployment of its warship flotillas, including submarines, in the Indian Ocean region in waters around India. The official reason cited by China is its prolonged deployment for intensive counter-piracy patrols in the Gulf of Aden and off the Horn of Africa.

But the Indian and US navies find little operational logic in the Chinese deployment of submarines - some of which have been nuclear-powered - for the stated task. Two submarines of the PLAN were known to have docked in a Pakistani port last year.

The Indian Navy has now proposed to host Bangladeshi crews who will operate the Chinese-built submarines at three of its schools in INS Satavahana: the Submarine Training School (SMS), the Escape Training School (ETS) and the School of Advanced Undersea Warfare (SAUW).

This is also where the Indian Navy has in the past hosted Vietnamese naval crew. Both the Indian and Vietnamese navies operate Russian-origin Kilo-class submarines.

An agreement to train Vietnamese fighter pilots in India was reached last month during talks led by the south east Asian nation's defence minister who was in New Delhi at the head of a 30-member delegation.

The two sides initially were planning for a team of Indian Air Force instructors to be deployed in Vietnam. But they then changed the plan and agreed that the Vietnamese pilots should be hosted at IAF bases.

India is also understood to be in talks with Vietnam to supply Akash medium-range surface-to-air missile (SAMs) systems. The SAMs - developed by the Defence Research and Development Organisation (DRDO) and now being inducted into the Indian Army and the Indian Air Force - have a range of 25km.

The DRDO claims they can intercept targets - such as incoming missiles - at a height of 20km after being activated.