The Pakistan Navy recently parked one of its submarines in the middle of Chinese Navy warships visiting Karachi. The strong defense ties between Pakistan and China are well reported. Currently the Pakistani Navy is massively growing its submarine branch with eight Chinese-designed Type-039B Yuan Class boats. Parking the sub there shows that the two navies are sharing knowledge as well as hardware.
The presence of the submarine is evident in commercial satellite imagery. It is hard to spot by the untrained eye so it has taken time to confirm it. And we can now be sure that it was a Pakistani sub and not Chinese. I can positively identify the submarine as an Agosta-90B type submarine, which is only operated by the Pakistan Navy. They are known locally as the Hashmat-class.
The Chinese Navy warships were visiting Karachi for a joint exercise, ‘Sea Guardian-2020’ in January. When I wrote about the exercise in April, showing the Chinese Warships in Karachi, the submarine was just visible in the imagery. But it had not been identified.