A new type of Chinese submarine spotted in satellite images puts a spotlight on Beijing’s efforts to improve both the quality and quantity of its boats, raising eyebrows in Tokyo and the region.

The sub, spotted in images taken May 29 at Jiangnan Shipyard in Shanghai and provided to The Japan Times by U.S. satellite company BlackSky, features a dramatically smaller sail and larger dimensions — approximately 120 meters long and 10 meters wide — than China’s Type 093 nuclear-powered attack submarine, according to several experts who examined the imagery.

The experts said that the vessel was highly likely to be a new type of nuclear-powered attack submarine with boosted stealth capabilities and improved range.