Vietnamese Defence Minister General Ngo Xuan Lich called on Prime Minister Narendra Modi here on Tuesday.Modi recalled his visit to Vietnam in September when the bilateral relationship was upgraded to a Comprehensive Strategic Partnership, said a statement from the Prime Minister's Office."Vietnam is a key pillar of India's Act East policy," the statement quoted Modi as saying."General Ngo briefed the Prime Minister on the progress achieved in bilateral defence cooperation. The PM noted that India and Vietnam have a longstanding and mutually beneficial relationship in the field of defence, and reiterated India's resolve to strengthen defence ties further."Modi said closer cooperation between India and Vietnam in all sectors would contribute to the stability, security and prosperity of the entire region.During Modi's visit, India offered a $500-million defence credit line, a part of which will be used for the construction of offshore patrol boats by, among others, the Vietnam Border Guards.Vietnam is among the countries which have a dispute with China over the South China Sea.