[10] In late May 2010, Bruce Cumings, a University of Chicago expert on Korean affairs, commented that the sinking should be regarded as part of long-running tensions in a naval no-man's land.

Combined Forces Command at the time had, on 24 March, testified before the US House Appropriations Committee, in part, on the need to strengthen the ROK-U.S. alliance, the need for on-site advanced training of the Air Force, the need to improve the quality of life and provide tour normalization for troops serving one-year tours, planned relocation of bases, and the scheduled 2012 transition of Operational Control (OPCON) to ROK hands.

[19][20] This caused the ship to break in half five minutes afterward, sinking at approximately 9:30 pm about 1 nautical mile (1.9 km) off the south-west coast of Baengnyeong Island.

[27][28] Early reports also suggested that South Korean navy units had shot at an unidentified ship heading towards North Korea, but a defense official later said that this target may have been a flock of birds misidentified on radar.

[15][31][37] On 30 March 2010 it was reported that one South Korean naval diver (ROKN UDT/SEAL CWO Han Ju-ho) had died after losing consciousness while searching for survivors, and another had been hospitalised.

[39] On 15 April 2010, the stern section of the ship was winched from the seabed by a large floating crane, drained of water and placed on a barge for transportation to the Pyongtaek navy base.

[44] Later South Korea announced that it intended to form an international group to investigate the sinking including Canada, Britain, Sweden and Australia.

[48] The Washington Post reported on 19 May 2010, that a team of investigators from Sweden, Australia, Britain, and the United States had concluded that a North Korean torpedo sank the ship.

[50] On 7 May 2010, a government official said that a team of South Korean civilian and military experts[51] had found traces of RDX, a high explosive more powerful than TNT and used in torpedoes.

The inquiry also alleged that a group of small submarines, escorted by a support ship, departed from a North Korean naval base a few days before the sinking.

[5] Investigators were reported to believe that the submarine fired the torpedo from about 3 km (1.9 mi) away, timed for a period when tidal forces in the area were slow.

Some critics have pointed out that these markings are inconsistent with North Korean practices, as the character "번" is not commonly used there, with "호" (romanized: ho) being used in its place instead.

[66] According to a survey conducted by Seoul National University's Institute for Peace and Unification Studies, less than one third of South Koreans trust the findings of the multinational panel.

[69] Lee Jung Hee, a lawmaker with the opposition Democratic Labor Party, was sued for defamation by seven people at South Korea's Joint Chiefs of Staff.

Lee said during a speech in the national assembly that while the Defense Ministry had said there was no feed from a thermal observation device showing the moment the warship's stern and bow split apart, such a video did exist.

Prosecutors then questioned Shin Sang-cheol, who served on the panel that investigated the incident and also runs Seoprise, over his assertion that Cheonan sank in an accident[70] and that the evidence linking the North to the torpedo was tampered with.

[65] Shin wrote a letter addressed to US Secretary of State Hillary Clinton showing the evidence for his contention that the ship ran aground and then collided with another vessel.

It was claimed that the assessment concluded Cheonan was not sunk by a North Korean bubble jet torpedo, but did not come to any firm conclusion about the cause of the sinking.

[78] According to The Hankyoreh, the Russian investigators concluded that Cheonan touched the sea floor and damaged one of its propellers prior to a non-contact explosion, possibly caused by setting off a mine while the ship was trying to maneuver into deeper water.

It calculated that the seismic data recorded would be accounted for by a 136 kg (300 lb) TNT-equivalent charge, similar to the explosive yield of land control mines which had been abandoned in the vicinity.

[94] Admiral Kim Sung-chan, at a publicly televised funeral for Cheonan's dead crew members in Pyeongtaek, stated that, "We will not sit back and watch whoever caused this pain for our people.

[97] Writing in The New York Times, Korea scholar Brian Reynolds Myers stated that there was not much anger or outrage among ordinary South Koreans over the sinking.

[102] The decision to cease trade was followed up with the United States and South Korea announcing they would conduct joint naval exercises in response to the sinking.

South Korean military propaganda FM broadcasts were resumed at 18:00 (local time) starting with the song "HuH" by K-pop band 4minute.

On 8 May 2010, a former senior presidential secretary who served under Roh Moo-hyun, Park Seon-won,[108] was charged with libel by South Korea's Defense Minister, Kim Tae-young, over comments he made during a 22 April interview on MBC radio asking for greater disclosure from the military and government.

Park Seon-won's response to the charge was: "I asked for the disclosure of information for a transparent and impartial investigation into the cause of the Cheonan sinking;" he added that "the libel suit seeks to silence public suspicion over the incident.

Said the board, "Military officers deliberately left out or distorted key information in their report to senior officials and the public because they wanted to avoid being held to account for being unprepared.

[111][112] North Korea's Korean Central News Agency (KCNA) released an official response to the investigation on 28 May 2010 stating that part of a torpedo doing so much damage to a ship would not survive: Besides, the assertion that the screw shaft and engine remained undamaged and unchanged in shape is also a laughing shock.

Even U.S. and British members of the international investigation team, which had blindly backed the South Korean regime in its 'investigation', were perplexed at the exhibit in a glass box.

The defector, known by the alias "Ahn Cheol-nam", stated that the captain, co-captain, engineer, and boatswain of the mini-sub which sank Cheonan had been awarded "Hero of the DPRK" in October 2010.