NEW DELHI: One of the first satellite imageries of two Chinese submarines, including a nuclear one, docking at Karachi in May last year, was made public today, highlighting the growing military ties between China and Pakistan in India’s backyard.The image posted on Twitter by a satellite imagery expert (@rajfortyseven) shows two Chinese PLA Navy submarines docking at Karachi. The submarines are the Type 091 Han-class nuclear powered submarine and the Type 039 Song-class diesel electric submarine.The Type 091 submarine can fire variants of anti-ship missiles and indigenous and Russian torpedoes. These Han class submarines are known for being noisy and having high internal radiation levels. But they have the capability to strike at shipping lanes beyond China’s coastal waters.The first of the Han class submarines, was laid down in 1967 and was commissioned in 1974.But unlike conventional submarines, nuclear ones can operate for a longer period of time. The Type 039 is a diesel electric submarine. It has been designed to attack both submarines and surface ships with torpedoes. Its primary weapon is the 533 mm Yu-4 torpedo, a locally produced passive homing 40-knot torpedo.The presence of Chinese submarines in the Indian Ocean underlines the issue of Beijing competing with India for dominance in a region which is strategically important for India.But this is not the first time Chinese submarines have been spotted in the Indian Ocean region. Chinese submarines had docked at Colombo in 2014 and at Karachi in May, 2015. China had then said its vessels are not directed against a third party and its movements are open and transparent.Indian Navy chief Admiral Sunil Lanba in December last year confirmed that Chinese military ships have made several port calls in Karachi. He also said India is monitoring their movements in the Indian Ocean region, adding the Indian Navy has the capability to take on any force.