Based on all the relevant facts and analyses of the classified information, the JIG and MCITF reached the following conclusion: ROKS Cheonan was sunk due to an underwater explosion caused by an attack of a CHT-02D torpedo manufactured and used by North Korea. The evidence points overwhelmingly to the conclusion that the torpedo was fired by a North Korean submarine. There is no other plausible explanation. ---Excerpt from Summary

The damage conditions that would be present in case of a grounding such as longitudinal cutting effects, hull scratch, sonar dome and propeller damage (located under hull bottom), and others were not present. In addition, it is confirmed that there are no known reefs in the incident sea area. Furthermore, since dishing effect (normally generated from underwater explosion) was apparent on the bottom shell plating, the possibility of damage from reefs or other grounding events was rejected.---Excerpt from Analysis on Possible Causes of the Sinking

The ROK ADD, UK, and US investigation teams made the assessment that the explosive was precisely guided to the center of the ship where it exploded in the proximity of below the gas turbine room 3m to the portside from the center, where the shockwave and bubble effect generated by the explosion caused the separation of the ship.
Therefore, there is a high possibility of a torpedo attack. An acoustic guided torpedo which can be launched from a submarine is assessed to be the likely weapon system used.---Excerpt from Analysis on Possible Causes of the Sinking

Analyzing the collected items revealed that ROKS Cheonan was hit and sunk by an underwater weapon carrying mixed explosive composed of HMX (527.91ng in 28 items), RDX (70.59ng in 6 items), and TNT (11.7ng in 2 items) ---Excerpt from Evidence Analysis

Results of the survivors' and sentries' testimony analysis revealed the following: many crew members had floated into the air before falling; two crew members heard the explosion sound twice; no one saw flames, fire or water columns, and no one suffered burn wounds; some personnel suffered from fractures and bruises; many of the survivors believed that a torpedo caused the incident; furthermore, sentries testified they heard the noise and witnessed the flash of light. Considering all the observations above, these are consistent with the UNDEX bubble effect phenomenon. ---Excerpt from Testimony Analysis

Ships of Navy Search and Rescue Group and of KORDI identified 30 objects underwater in total in the vicinity of ROKS Cheonan's sinking site. Most of the objects were confirmed to be debris of ROKS Cheonan, bedrock, and abandoned fishing net which could not have affected the sinking of ROKS Cheonan. ---Excerpt from Analysis on Sea Area of the Incident -

The facts that the evidence, the propulsion device of torpedo, matches in size and shape with the blueprint of North Korean CHT-02D torpedo with Korean alphabet ('1번‘: No.1) marked on it, and that the inventory inspection on ROKN underwater weapons resulted with no missing assets, indicate that the propulsion device of torpedo collected near the origin of explosion is the remains of CHT-02D torpedo manufactured in North Korea. This confirms the assessment that ROKS Cheonan was sunk by the explosion of a North Korean CHT-02D torpedo. ---Excerpt from Propulsion Motor System of Torpedo -

ROKS Cheonan was split and sunk due to shockwave and bubble effect generated by the underwater explosion of a torpedo. The detonation location was 3m to port from the center of the gas turbine room and at a depth of 6~9m. The weapon system used was a CHT-02D torpedo with approximately 250kg of explosives manufactured and used by North Korea.