Type 091 Han-class - Service

Five Han's had been in the PLAN inventory since the early 1990s, though the operational status of the individual submarines tended to fluctuate as boats undergo refits. The first two submarines of the class underwent their mid-life refits in the late 1980s. 403 and 404 began their refits in 1998 and returned to service in 2000. The 405 submarine began its mid-life refit in 2000 which was believed to have been completed in 2002. In September 2003, 401 boat was retired. In 2005, 402 boat was retired.

In February 1975, the first nuclear submarine detachment of the Chinese Navy was formed in the North Sea Fleet. On August 3, 1975, the 401 boat was designed and produced. From 1977 to 1990, four 091-type attack nuclear submarines were successively built, named Long March 2 to Long March 5, and boats 402 to 405 were deployed in Qingdao Port of the Chinese Navy North Sea Fleet.

Over the course of a three-day encounter that began on 27 October 1994 about 100 km west of Kyushu, Japan, a Han-class submarine shadowed the USS Kitty Hawk (CV 63) battle group in the Sea of Japan. The submarine was tracked by a US Navy S-3B ASW aircraft from the aircraft carrier Kitty Hawk off the Korean coast. This prompted a several [reports say two or three] Chinese J-6 fighters to intercept the "hostile" American S-3 ASW aircraft on 28 October. No communications took place between the aircraft. The submarine eventually approached within about 30-km of the Kitty Hawk, rather closer than normally envisioned by carrier battlegroup operational procedures.

After the 1990s, two ships were transferred to the Chinese Navy's South China Sea Fleet to serve to strengthen the maritime combat power against the South China Sea and Taiwan. Erickson and Goldstein noted that the "conventional wisdom in China’s naval literature ... tends to credit China’s Han submarines with a significant role in the 1996 Taiwan Strait crisis. Thus, one report states that in mid-March 1996, “U.S. military satellites were unable to detect the position of [certain] Chinese nuclear submarines; it was as if they . . . had vanished.” This narrative continues, “The U.S. carrier battle groups were unable to cope with the hidden, mobile, highspeed, undersea” threat posed by the Chinese nuclear submarines, and thus “were unable to approach the sea area within 200 nautical miles of Taiwan.” Implying some uncertainty on this issue, the author asks, “Why did the U.S. carrier group suddenly change its original plan? Was it that they feared China’s nuclear submarines?” Another PRC report also alleges that American military satellites lost track of China’s SSNs and that the U.S. Navy was forced to retreat when confronted by the “massive threat of China’s nuclear submarine force.” Given the Han-class SSN’s reputation as a noisy vessel, these statements might well be viewed with suspicion".

On 10 November 2004 a submarine, believed to be a Han-class nuclear powered vessel, spent two hours submerged in Japanese waters, near Taiwan. The submarine entered the Pacific Ocean region of Japan's territorial waters in the southwestern sector of Okinawa prefecture, about 400 kilometers southwest of Okinawa island. It slipped between the remote Miyako and Ishigaki islands at a speed of about 10 knots before returning to Chinese waters. It was cruising in shallow waters about 300 meters below the surface, making it relatively easy for the MSDF to locate. The incursion prompted Japan's maritime forces to go on alert for only the second time since the end of World War Two. Japan mobilized its maritime forces and chased the sub with destroyers and a patrol plane as it zigzagged submerged toward Chinese waters. Tokyo followed the fleeing intruder using its P-3C Orion aircraft and two MSDF destroyers. Japan's Maritime Self-Defense Force (MSDF) had apparently detected the submarine several days earlier as it cruised submerged near Japan's maritime border.

On 16 November 2004 Japan said China admitted the mystery submarine was one of its own, and expressed regrets. Japan's Foreign Ministry said the message was conveyed by Chinese Vice Foreign Minister Wu Dawei to Japanese Ambassador Koreshige Anami in Beijing. Tokyo said Beijing told it the submarine was on a training mission, and for "technical reasons," it ventured into Japanese waters. Foreign Ministry Assistant Press Secretary Akira Chiba says China's official response also contained an apology. "We take it as an official apology since the word 'sorry' was used. On the other hand, we have asked them to prevent such incidents from happening again and for that we have haven't gotten any response yet." China's Foreign Ministry was more circumspect about the matter. At a regular briefing in Beijing, Foreign Ministry spokeswoman Zhang Qiyue would only say that China had passed on information to Tokyo.

Japan's trade minister says he believed that a Chinese submarine was linked to gas exploration by China in a remote island area claimed by both countries. Japan, China and Taiwan all claim possession of a speck of islands called Senkaku in Japanese and Diaoyu in Chinese. They are about 500 kilometers from Japan's Okinawa Island and 140 kilometers from Taiwan.

The first unit of this class [401] had certainly been withdrawn from service, possibly in 2000, the next newest boat [402] appeared to have withdrawn from service soon thereafter. In 2009, the No. 403 boat was publicly unveiled at the 60th anniversary of the Chinese Navy. The three newest boats (403, 404, and 405) remained in service as of 2019. The US Department of Defense's Annual Report to Congress on The Military Power of the People's Republic of China for 2006 and 2007 reported that the PLA Navy had 5 nuclear submarines, which might be taken to mean 1 SSBN, 1 new Type 093 Shang SSN, and three Type 091 Han boats.

People's Liberation Army (PLA) Daily reported 29 October 2013 that China had decommissioned its first nuclear-powered submarine after more than 40 years of service in the military. According to this report, the submarine's nuclear devices had been properly disposed of and scientists have decontaminated the warehouse where nuclear items were stored during the past 40 years. The submarine will be used as an exhibit after it is released from military service, according to the newspaper. Disposal of the decommissioned nuclear submarine is a difficulty for countries using nuclear ships all over the world. A submarine base of the PLAN spent ten years to work out a disposal method with Chinese characteristics. In 2017, the No. 401 boat was opened to the public at the Qingdao China Naval Museum.