India has signed an agreement for surveying coastal waters with Vietnam, a country on the doorstep of China—a factor which is adding a strategic dimension to New Delhi-Hanoi ties.

On Friday, Defence Minister Rajnath Singh signed the Hydrographic cooperation agreement with his Vietnamese counterpart General Ngo Xuan Lich. This will allow the two countries to share hydrographic data and assist them in the production of navigational charts. Tweeting about the agreement, Singh said: “Had a fruitful interaction with my Vietnamese counterpart General Ngo Xuan Lich during a virtual bilateral meeting. We discussed ways to further the Comprehensive Strategic Partnership & friendship between both the countries. Our defence cooperation has expanded considerably.”

A significant agreement, hydrography allows the navies to determine sea depth, chart out seabed and sea routes and figure out where it is safe for ships to sail. It helps navies plan military exercise and operations.

Vietnam has also invited the Defence Minister to the ASEAN Defence Minister’s Meeting Plus (ADMM) to be hosted virtually on December 10. Singh added that the two nations will also conclude an institutionalised framework agreement in the near future.

India-Vietnam ties are being steered by a Comprehensive Strategic Partnership (CSP). The pact signed in September 2016, during Prime Minister Narendra Modi visit to Hanoi has amplified India’s Act East Policy—a doctrine to engage with Southeast Asia and the islands of the Pacific Ocean, with the 10-member Association of South East Asian Nations (ASEAN) at its heart.

With Beijing posing a common threat to both Vietnam and India—countries which have each fought a border war with China—the growing relationship between New Delhi and Hanoi has acquired a strong security and geopolitical dimension. Vietnam has been in China’s crosshairs in the South China Sea. The friction between the two had peaked when the Chinese sank a Vietnamese fishing boat near the disputed Paracel Islands in the SCS.

India, on its part, is engaged in a stiff military standoff with China in Ladakh. With common interest in the Indo-Pacific, an area on either side of the Malacca straits, India and Vietnam have recently become part of what is called a Quad-plus grouping. That includes India, the United States, Japan, Australia, New Zealand and Vietnam..